Increasing diversity of COVID-19 strains: insights into evolutionary divergence and public health

 To be clear, I am not a virologist, nor am I a public health expert. But I do know how to analyze patterns of evolutionary diversity. Research into the SARS-CoV-2 virus that has given rise to the COVID-19 pandemic has greatly enhanced our understanding of global disease dynamics, mRNA vaccines and public health responses to a global crisis. But the COVID-19 pandemic also has the potential to provide fundamental insights into basic ecological and evolutionary processes. 

While a lot has been written about how COVID-19 lock-downs have had noticeable repercussions on air quality and wildlife in cities, the virus lends itself as a microcosm into natural world dynamics. SARS-CoV-2 is now the most studied non-human organism on Earth, and we've witnessed its spread across the globe (which provides insights into invasion biology), it has spread exponentially in populations at times (showcasing the power of models to predict spread), and its rapid diversification is evolution in real time.

Understanding how SARS-CoV-2 strain diversity is generated is of fundamental importance for public health policies. And SARS-CoV-2 is evolving and diversifying. In Ontario, Canada, we have a wonderful resource from Public Health Ontario that publishes data on the evolution of strain diversity and provides a wonderful graphical interface. This interface focuses on the SARS-CoV-2 phylogeny (that is the evolutionary family tree connecting strains to their ancestors) in Ontario.

An example phylogeny

Using their open data, I addressed a simple question, is the evolutionary diversity (measured by the distances separating strains) increasing over time?

To test this, I calculated a statistical measure called the standardized effect size of the mean pairwise distances (SES.MPD) which quantifies the average distances separating strains standardized by random permutations (in this case 500 randomizations) so that a SES.MPD value of 0 means that the evolutionary diversity of a group of strains is no different than a same number of strains randomly selected from the phylogeny. Negative values mean that strains are more closely related on the phylogeny than you expect by chance (referred to as under-dispersed), and positive values mean strains are more distantly related (over-dispersed). I did these calculations for each month since the pandemic hit Ontario (March 2020) and for the seven different regions of Ontario.

Analysis of the standardized effect size of the mean pairwise distances (SES.MPD) of SARS-CoV-2 strains across the seven regions in Ontario since the start of the pandemic. The dashed horizontal line indicates a value of 0 (no different than random expectation) and points outside of the grey box are statistically significantly different than random.

What I found was that early on in the pandemic, the strains were under-dispersed, meaning that they were more closely related and genetically similar than expected by chance. But over time the dissimilarity between strains increases and by May 2021 (the last data in the graphs), many of Ontario's regions had significantly over-dispersed strains. This means that strains found in the populations in May 2021 were generally more dissimilar from one another than early on.

Why this matters is that vaccines and other treatments are typically developed on a single strain or from samples collected at a specific time point. If strains are relatively genetically similar, then it is highly probable that treatments will be successful across the strains. However, as strains diversify and become more dissimilar, then treatments might become less effective overall. 

Had the spreading infection been dominated by single strains, with very few newer strains replacing older ones, we would expect that the SES.MPD values remain below zero, and would make it easier to track strains and adapt treatments.

These patterns are also valuable for insights into ecology and evolution. We often look at SES.MPD values to interpret how different processes structure diversity (like competition, predation, pollution, etc.), but we often don't have good evidence of how historical evolutionary processes can drive SES.MPD differences. The plots above show that rapid evolutionary diversification results in linearly increasing SES.MPD values.

Targeting Biodiversity Conservation: A Post-2020 World

Guest post by Connor Kendall, recent MEnvSc graduate from the University of Toronto-Scarborough

The world is currently in the midst of the sixth mass extinction where global vertebrate populations have declined by 60% over the past 40 years and human pressures are impacting a vast 75% of the Earth’s surface¹. If we continue along the path of business-as-usual, we will have a lot more to be concerned about than just living underwater in the next 30 years. If we lose most of the world’s pollinators, 40% of which are facing extinction¹, you can say goodbye to your avocado toast and pumpkin spice lattes. If bats continue along their current trajectory and become extinct, you can say hello to endless summer nights with countless mosquito bites. This is why we need global action towards conserving, restoring and sustaining biodiversity, which is exactly what the Aichi Biodiversity Targets hoped to accomplish back in 2010.

Source: UNDP (2013). Charting pathways for biodiversity and sustainable development (retrieved from: https://www.slideshare.net/equatorinitiative/charting-pathways-for-biodiversity-and-sustainable-development)

At the 10^th meeting of the Conference of the Parties in 2010, the Strategic Plan for Biodiversity 2011-2020 was implemented and the 20 internationally agreed upon Aichi Biodiversity Targets were formulated. The goal of this plan was to “take effective and urgent action to halt the loss of biodiversity” by 2020. The years have since gone by and it is now 2020, so what does that mean for the targets and biodiversity conservation? We are still experiencing unprecedented species declines – and despite global commitments towards achieving these targets, as a whole – we fell short and a lot still remains to be done. There is no point dwelling on the past but rather, it is important to learn from our failures and look to the future in order to adapt and create revised targets. We need to refocus our efforts, now more than ever, so that we can transform our relationship with nature and save the things we hold dear (even if that is just avocado toast).

Before we can look to the future, we must first look to the past. Where did we fall short? What can we learn from our failures? Did we miss something? These are the questions that need to be answered if we want to succeed in the future. In writing this blog about the past and future of International Biodiversity Targets, I hope to draw attention to the issue of biodiversity loss and highlight the importance of not only creating these targets but also achieving them, in the years to come.

Where did we go wrong?

It’s been 10 years since the 20 Aichi Biodiversity Targets were agreed upon and we have fallen short of almost all of them. The targets have been criticized for being too ambiguous leaving room for interpretation, not being quantifiable enough making it difficult to track progress, and not being binding which allowed countries to create individualized targets that don’t meet the global targets. Together, these may be a couple of the reasons why we have failed to meet the majority of the goals globally.

Let’s take a look at Aichi Target 11 which is one of, if not the most, talked about target. Target 11 falls under the Strategic Goal C and states:

 

“By 2020, at least 17 per cent of terrestrial and inland water, and 10 per cent of coastal and marine areas, especially areas of particular importance for biodiversity and ecosystems services are conserved through effectively and equitably managed, ecological representative and well-connected systems of protected areas and other effective area-based conservation measures, and integrated into the wide landscapes and seascapes.”

 

As far as the target itself goes, it is one of the most quantifiable and easily tracked targets, providing exact percentages of area that must be conserved. It is specific and uses unambiguous language, providing clear guidance on how to achieve the target. Areas must be ecologically “representative”, “well-connected” and “effectively and equitably managed”. Seems fairly straight-forward, right? Wrong. Because the Aichi Biodiversity Targets are not binding and act more as a guide than a hard-and-fast rule, different government agencies can take these “guidelines” and adjust them into what works for them. For example, in 2015 (five years after the original targets were imposed) Canada came up with their own 2020 Biodiversity Goals and Targets, giving them just a couple of years to make any real progress. The issue with these targets is that they removed a lot of the meat from the Aichi Targets, solidifying the dreary fate of biodiversity. For comparisons sake, let’s take a look at Canada’s Target 1, to see just how Aichi Target 11 was altered:

 

“By 2020, at least 17 percent of terrestrial areas and inland water, and 10 percent of coastal and marine areas, are conserved through networks of protected areas and other effective area-based conservation measures.”

 

What was once 62 words has been condensed down to 32. The main idea of the target and the percentages are still there however, it leaves out the idea of conserving ecologically representative areas that are effectively and equitably managed. By removing these ideas, Canada made a more ambiguous target and set themselves up to achieve the target in all the wrong ways. And Canada is not alone.

The Protected Planet issued a report in 2018 and have since updated it with information from February 2020. According to this report, 15.1% of the global terrestrial area and 7.9% of the global marine area have been conserved. 

Source: UNEP-WCMC and IUCN (2020). Protected Planet: The World Database on Protected Areas (WDPA), February 2020 version (retrieved from: https://livereport.protectedplanet.net)

Looking at these numbers, it seems like we are heading in the right direction but, when you dive further you notice that is not the whole picture. Remember in the Aichi Target 11 when it specified the areas needed to be “representative”, “well-connected” and “effectively managed”? The Protected Planet Digital Report looked at the percentage of areas that are conserved that meet each of these criteria and this is what it found: 5% of terrestrial areas and 1% of marine areas are effectively managed, 9% of terrestrial areas are ecologically representative, and 7% of terrestrial areas are well-connected.

Source: UNEP-WCMC and IUCN (2020). Protected Planet: Aichi Target 11 Dashboard (retrieved from: https://www.protectedplanet.net/target-11-dashboard)

Because the countries had the ability to adapt the Aichi Targets to suit their needs, it left too much room for ambiguity and inadequacy, ensuring that by 2020, there was nothing the world could do but fall short. It is important when we look to the future of biodiversity conservation that we consider the mistakes from the last 10 years and learn from them to ensure biodiversity is around for the generations to come.

What does the future look like?

The future remains uncertain but what is certain, is the need to act now. Many believe that new targets must be SMART (specific, measurable, attainable, relevant, time-based), should integrate scientific research where applicable, and involve progressive steps and actions similar to a roadmap for achieving the targets.

Negotiations have already been underway and governments have given themselves two years to develop a post-2020 framework that is to be presented at the 15^th Conference of the Parties, at the UN Biodiversity Conference in 2020 in Kunming, China. An open-ended intersessional working group, under the leadership of Mr. Francis Ogwal of Uganda and Mr. Basile van Havre of Canada, has already published the Zero Draft of the Post-2020 Global Biodiversity Framework as of January 13th, 2020. The framework hopes to provide both the context and structure required to allow diverse stakeholders to communicate and work together towards the common goals.

The zero draft looks to the next decade and identifies a 2030 Mission:

 

“To take urgent action across society to put biodiversity on a path to recovery for the benefit of planet and people.”

 

The post-2020 framework also proposes 20 new biodiversity conservation targets. What is interesting about the proposed targets is that there are similarities to the original Aichi Targets and it is evident that the working group considered the mistakes that were made and learned from them when drafting the new ones. For example, the second proposed target mirrors Aichi Target 11 and ups it by creating the more ambitious proposed Target 2:

 

“Protect sites of particular importance for biodiversity through protected areas and other effective area-based conservation measures, by 2030 covering at least [60%] of such sites and at least [30%] of land and sea areas with at least [10%] under strict protection.”

 

The target not only identifies higher percentages of area protected, but also offers up the condition of “strict protection” which was not included in the original Aichi Target 11.

It is also evident in the new proposed targets that the working group listened to the public over the past decade and tried to incorporate issues that people care about like plastic waste in proposed Target 4, climate change mitigation and adaptation in proposed Target 6, and the sustainable use of wild species in proposed Target 7. In order to stand a chance of reaching the goals by 2030, it is clear that the public needs to be engaged with these targets, and what better way to do it than include things that people are already passionate about.

The Zero Draft of the Post-2020 Global Biodiversity Framework is promising and it has huge potential to have a ripple effect in many countries, but there are some things that need to be reviewed and reconsidered before that can happen. Some of the targets remain to be unquantifiable, such as the proposed Targets 16 and 17. At the very least, the working group should consider including some guidelines as to how to achieve and track these targets, to ensure they do not get lost and forgotten alongside some of the “bigger ticket” targets.

Any new framework that is implemented will have its highs and lows, but to ensure the 2030 Mission and Targets are achieved in the best way possible, it is important that the new framework works on strengthening the existing Aichi Targets, progress and initiatives that are underway and learn from them, as well as have stricter guidelines in place to avoid the ambiguity and inadequacy that came about from the Aichi Targets.  

All hope is not lost, but much still remains to be done. Now, more than ever, we need a drastic shift in the way biodiversity is viewed and valued in order to stand a chance of putting an end to the sixth mass extinction and the post-2020 framework is a step in the right direction.

 

1.     WWF (2018). Living Planet Index. Retrieved from: https://www.worldwildlife.org/pages/living-planet-report-2018 

Southern Ontario’s Ecoregions in Slow Motion: An Eight-Year Journey Along the Bruce Trail

Guest post by Daniel Stuart, MEnvSc Candidate in the Department of Physical & Environmental Science at the University of Toronto-Scarborough

During the final year of my undergraduate program the idea of hiking all 900-or-so kilometres of the Bruce Trail somehow lodged itself in my head. It was 2010 and I was twenty-one years old, immersed in the idealism of that age and on the doorstep of a career as an ecologist. At the time hiking from Queenston Heights along the Niagara River to the town of Tobermory at the northern tip of the Bruce Peninsula (Figure 1.) seemed an appropriate way to gain a more meaningful appreciation of my home province’s landscape. This would turn out to be true in part, but little did I know that the more valuable takeaway would be a practical education in the transitional ecosystems that define Southern Ontario’s landscape. For those without the time to hike it themselves, take a tour with me along the trail from south to north exploring its subtle but undeniable ecological shifts.

Figure 1: Bruce Trail Map (Bruce Trail Conservancy, 2020

As life sometimes goes, it was another two years before I finally purchased the Bruce Trail Reference guidebook and embarked on my first sojourn, a three day hike that would take me from the southern terminus of the trail at Queenston Heights back to Hamilton where I lived at the time. I hopped on a free shuttle bus heading for a casino in Niagara Falls and upon arriving was accosted by the bus driver when he spotted my backpack and water jug, realizing I had no intention of gambling that day.  It was September 2, 2012 and the first miles of the trail were peppered with sightings of uncommon shrubs and trees like Bladdernut (Staphylea trifolia), Sassafras (Sassafras albidum), Spicebush (Lindera benzoin), Pignut Hickory (Carya glabra), and Hill’s Oak (Quercus ellipsoidalis), many of which display full fruit in the late summer. These shrubs and trees share a common trait: in Canada they are confined to the Carolinan Ecoregion.

The Carolinan Ecoregion (defined as Ecoregion 7E in Ontario; Figure 2.) occupies the southernmost portions of Ontario, extending from the shores of Lake Erie to approximately Grand Bend in the west, London, Hamilton, and Toronto in the east. Named for the forests typical of the Atlantic Coast from Long Island to Georgia, this region is dominated by a large variety of deciduous (or, leafy) trees including those listed above that fail to thrive in cooler climates to the north or west (Colthurst & Waldron, 1993). In the Niagara Region the sheltering cliffs and slopes of the Niagara Escarpment offer a slightly warmer microclimate that encourages the region to “punch above its weight” in terms of plant diversity.

Figure 2: Ecoregions of Ontario (Crins et al., 2009)

My first journey from the Niagara River ended in utter failure when with painfully blistered soles, just 26 kilometres into my expedition I swallowed my pride and called a friend to pick me up at the Brock University campus in St. Catharines. I would eventually work up to 30- and even 40-kilometre days, but this would take years of training and a good deal of re-conditioning every spring to tighten up my legs that would seemingly turn to jelly each winter.

The “southern feel” of the Bruce Trail gradually diminishes as one hikes westward toward Hamilton, the conspicuously common open-grown oaks (Quercus spp.) gently replaced by the familiar Sugar Maple (Acer saccharum)-dominant woodlands that emblemize Canada. The extensive forested tracts of the Dundas Valley offer the final display of southern species before mounting the escarpment where suddenly one stands firmly in the Great Lakes-St. Lawrence Ecoregion (defined as Ecoregion 6E in Ontario; Figure 2.).  The abruptness of the transition surprised me. I recall spotting the northernmost stand of a southern tree, a population of Chinquapin Oak (Quercus muehlenbergii) perched below the escarpment brow next to Sydenham Road in Dundas. Although I understand that southern species are occasionally found north of the official boundaries of the Carolinian Ecoregion, along the Bruce Trail I encountered no other Carolinian-specialist plant. The sheltered valleys of the Hamilton area seem to provide a last bastion for southern plants that struggle to tolerate the exposed landscape above Burlington and beyond.

From the Burlington heights the Great Lakes-St. Lawrence forest extends northward all the way to the edge of the Canadian Shield, which itself transitions into the seemingly endless Boreal forest that blankets the northern part of our continent. Unlike the Carolinian region which comprises mostly deciduous trees, or the Boreal region which compromises mostly coniferous trees, the Great Lakes-St. Lawrence forest is a roughly equal mix of the two. This forest type features strong representation from leafy trees like Sugar Maple (Acer saccharum), American Beech (Fagus americana), and Black Cherry (Prunus serotina) along with their needled counterparts like Eastern White Pine (Pinus strobus), Eastern White Cedar (Thuja occidentalis), and Eastern Hemlock (Tsuga canadensis).

I hiked the central stretches of the Bruce Trail at a slower rate between 2014 and 2018, a section that traverses a hilly complex of woodlots, river valleys, and bucolic landscapes. I came across a Striped Maple (Acer pensylvanica) in the Caledon area and a small Jack Pine (Pinus banksiana) stand on a north-facing slope near the Hockley Valley, both typically northern trees. My first Northern Holly Fern (Polystichum lonchitis) was observed in Noisy River Provincial Park near the village of Creemore, a plant that in places coated the trailside by the time I reached Owen Sound. Similarly, I spotted a tiny American Hart’s Tongue Fern (Asplenium scolopendrium var. americanum) in the Beaver Valley, a globally uncommon species whose core range is concentrated around Owen Sound and the lower reaches of the Bruce Peninsula.

By May of 2019 I was hiking in earnest, setting aside many weekends to cover the approximately 210 kilometres from the west edge of the Beaver Valley near Kimberley, through Owen Sound and to the base of the Bruce Peninsula near Wiarton. The birding that spring was glorious, and I often hiked with binoculars somewhat annoyingly tugging against my neck. In the Beaver Valley I observed my first ever Louisiana Waterthrush (Parkesia motacilla) along the rushing banks of Bill’s Creek. A Philadelphia Vireo (Vireo philadelphicus) flitted between branches in a woodlot near Walter’s Falls, a Golden-winged Warbler (Vermivora chrysoptera) was spotted within a thicket at the Bighead River Overnight Rest Area, and a Green Heron (Butorides virescens) squawked at me near the Bognor Marsh.

In early September 2019 I began the big push up the Bruce Peninsula toward Tobermory, in a four-day period that would take me from the town of Wiarton to Crane Lake Road just before the southeast boundary of Bruce Peninsula National Park. Logistics were more complicated now and I was forced to consider packing lightweight provisions that were adequate but could still be carried on my back. There were also safety considerations specific to the Bruce Peninsula, like establishing a check-in system where cell reception was poor, and to keep aware of Black Bear (Ursus americanus) and the docile but not entirely unthreatening Massasauga (Sistrurus catenatus), Ontario’s only venomous snake. Bear scat was an intermittent sight along the length of the peninsula, first observed just 14 kilometres past Wiarton along Malcolm Bluff.

Although forests remained of mixed composition typical of the Great Lakes-St. Lawrence region, cool northern exposures and thin-soiled areas took on a palpable “northern feel”, often dense with Eastern White Cedar (Thuja occidentalis), pine (Pinus spp.) and Eastern Hemlock (Tsuga canadensis). Wind-beaten crags offered habitat for abundant Bearberry (Arctostaphylos uva-ursi), a northern species yet unseen on my journey so far, and Rattlesnake Plantains (Goodyera spp.) became commonplace. By the time I reached the edge of the National Park the Boreal woods felt much closer.

Sadly, poor weather and low spirits cut my hike short in September, with soggy feet and an approaching storm promising to result in a miserable finale. Despite this setback my goal to finish the Bruce Trail remains firm. At this moment I have booked a campsite in the National Park this May 2020 and (barring any disasters) myself, along with three companions, will finish the final 40 kilometres toward the trail’s northern terminus.

To walk the Bruce Trail is to walk a cross-section of Southern Ontario. For me it has offered an education in landscape ecology earned by traversing it first-hand. It has been a limit-testing and a character-building experience. Although I now hike with a different outlook than my 21-year-old self, I must credit him with having the guts to recognize the journey’s value and for accepting its challenge.

References

Bruce Trail Conservancy. 2020. Explore the Trail. Bruce Trail Conservancy. <https://brucetrail.org//trail-sections>. Retrieved 13 February 2020.

Colthurst, K., Waldron, G. 2013. “What is a Carolinian Forest?”. Essex Region Conservation Authority. Carolinian Canada. <https://caroliniancanada.ca/legacy/SpeciesHabitats_Forests.htm>. Retrieved 13 February 2020.

Crins, William J., Paul A. Gray, Peter W.C. Uhlig, and Monique C. Wester. 2009. The Ecosystems of Ontario, Part I: Ecozones and Ecoregions. Ontario Ministry of Natural Resources, Peterborough Ontario, Inventory, Monitoring and Assessment, SIB TER IMA TR- 01, 71pp.

Why Honey bees aren’t the buzz

*Guest post by Shannon Underwood, a student in Marc's 'Causes and Consequences of Diversity' class.

When you think “Save the Bees”, most likely a Honeybee comes to mind – this is primarily because they have become the flagship species for the current bee crisis. Although responsible for bringing the much-needed attention to the impact humans are having on our bee populations, they greatly misdirect the public, making a large number of people significantly less aware of the other 4,000 diverse bee species we have in North America¹⁴ – our wild (native) bees: the ones we should be more concerned about.

Fig 1. Adapted from Wilson, Forister, and Carril 2017. Above figure shows the total amount of bee species survey-participants thought were in the United States.

Pollinators are responsible for supporting 35% of the global agricultural landscapes¹⁵. Outside of agriculture, 80-95% of the native flowering plants that are found in natural ecosystems rely on animal pollinators for reproduction¹¹. Pollination is a fundamental ecosystem service provided by a variety of animals, however most efficiently by wild bees. The unique evolutionary histories that bees share with native plants has resulted in the vast diversity of traits seen among them (Photo 1), and communities with greater bee diversity have shown to be more productive than communities with poorer diversity¹² - largely because of greater resource partitioning by the wild bees. Their foraging preferences, differences in body shapes and sizes, as well as some species ability to perform a more effective technique of pollination called buzz pollination, make wild bees the most important group of pollinators.

 

 Photo 1: Shows the different body shapes and sizes of some wild bees. This rich diversity reflects their unique coevolution with plants.

Bees are facing substantial reductions in their diversity, range and abundances worldwide¹. In North America, there are currently 12 wild bee species that are recognized as ‘threatened’ under the IUCN Red-list. Staggeringly, all 12 of these species belong to the genus Bombus- commonly referred to as the Bumblebee. Over that last 20 years, Bumblebees have become one of the largest victims of decline in North America - with four species that faced a 23-87% shrinkage in their geographic range, and a precipitous 96% reduction in their abundance². A leading cause of the declines in wild bee populations has been largely attributed to land-use change¹. While the human population continues to expand, accumulating amounts of their natural habitat is lost and replaced with agricultural and urban landscapes. The fragmented habitats that remain often have decreased accessibility to green spaces and poorer nesting opportunities for bees. Making it harder for them to grab a foothold in the community – these human-added stressors put our wild bees at a much greater risk for extinction.

Fig 3. Adapted from Szabo et al. 2012. Shows the decline in the occurrence of B. affinis (A), B. terricola (B), B. pensylvanicus (C), and all bumblebee species (D) between the years of 1980-1990 (green) and 2000-2010 (blue).

The second most prominent impact on wild bee abundance and diversity has been greatly linked to invasive species like the common Western Honey bee¹. The Honeybee, native to the Old World region, has become an invasive species in all areas outside of its origin³. Their uniquely large colonies and hive formation make them the most valuable pollinator to humans in agriculture management. Wild bee health and productivity is often reduced in agricultural landscapes because of the high use of pesticides and lower foraging opportunities⁷. To compensate for this, the honeybee has become a highly used technique worldwide because they can be easily transported to a field for crop pollination- many policies and conservation efforts tend to primarily focus on the protection of such managed bee species because of this. But the positive attention that the honeybee receives publicly leaves many people unaware that it is even invasive in North America.

Honeybees are generalists – a common characteristic for many invasive species⁸. They can forage up to 2-3km outside of their hive and will recruit other colony-workers once a good food source is found, in order to maximize their foraging products³. Because of their large numbers, they can greatly increase the foraging competition for our already-threatened wild bee species. Honeybees are also prone to several diseases and can increase the risk of transmission to our wild bee populations³. Although the honeybee is valuable in agricultural pollination for its cost and time efficiency, in many cases wild pollinators are better at pollinating than the honeybee alone (Fig. 4). The honeybee lacks the ability to perform buzz pollination - the amount of pollen a queen Bumblebee can deposit to a blueberry flower in a single visit would require a honeybee to visit the same flower 4 times⁹. These small and diverse organisms are thus extremely important for sustaining healthy natural ecosystems, and so it becomes increasingly significant that we find ways to support their abundance and diversity during this new human-dominated era.

Fig. 4. Adapted from Garibaldi et al. 2013. The figure shows that wild insects increased reproduction (y-axis) in all crops examined than the honeybee alone.

Cities are commonly viewed as human-dominated landscapes that are inhabitable for wildlife. However, some people argue that cities may actually be ecologically valuable to certain types of species like our insect-pollinators⁷. Cities often have less pesticide than the surrounding rural landscapes⁷, and the commonly used green infrastructures like green roofs, gardens, and parks can be extremely valuable to pollinators by offering more abundant and diverse foraging opportunities. Green infrastructure in cities is also recognized as being important for decreasing flight times and even providing habitat for certain species⁴. Many beekeepers highlight that one of the best things anyone can do to support wild bees is to transform their property into a bee sanctuary. Plant pollinator-friendly gardens and even incorporate bee hotels into your backyard as a way to offer wild bees more opportunities in developed areas. You can also take part in projects like “Bees In My Backyard”  and “Bumble Bee watch”  to help conservationists collect information on our current bee populations. More importantly, though, just becoming educated about the threats to our wild bees and spreading awareness to the people around you is a crucial step towards refocusing our pollinator conservation efforts, and bringing the attention away from the honeybee and rightfully onto our wild bees.

Literature cited

1.     Brown, Mark J. F., and Robert J. Paxton. 2009. “The Conservation of Bees: A Global Perspective.” Apidologie 40(3): 410–16.

2.     Cameron, Sydney A. et al. 2011. “Patterns of Widespread Decline in North American Bumble Bees.” Proceedings of the National Academy of Sciences 108(2): 662–67.

3.     Colla, Sheila R., and J. Scott MacIvor. 2017. “Questioning Public Perception, Conservation Policy, and Recovery Actions for Honeybees in North America.” Conservation Biology 31(5): 1202–4.

4.     Dylewski, Łukasz, Łukasz Maćkowiak, and Weronika Banaszak‐Cibicka. 2019. “Are All Urban Green Spaces a Favourable Habitat for Pollinator Communities? Bees, Butterflies and Hoverflies in Different Urban Green Areas.” Ecological Entomology 44(5): 678–89.

5.     Garibaldi, Lucas A. et al. 2013. “Wild Pollinators Enhance Fruit Set of Crops Regardless of Honey Bee Abundance.” Science 339(6127): 1608–11.

6.     Graham, Kelsey K. “Beyond Honey Bees: Wild Bees Are Also Key Pollinators, and Some Species Are Disappearing.” The Conversation. http://theconversation.com/beyond-honey-bees-wild-bees-are-also-key-pollinators-and-some-species-are-disappearing-89214 (February 20, 2020).

7.     Hall, Damon M. et al. 2017. “The city as a refuge for insect pollinators.” Conservation Biology 31(1): 24–29.

8.     “Invasive Species | U.S. Climate Resilience Toolkit.” https://toolkit.climate.gov/topics/ecosystem-vulnerability/invasive-species (February 21, 2020).

9.     Javorek, S. K., K. E. Mackenzie, and S. P. Vander Kloet. 2002. “Comparative Pollination Effectiveness Among Bees (Hymenoptera: Apoidea) on Lowbush Blueberry (Ericaceae: Vaccinium Angustifolium).” Annals of the Entomological Society of America 95(3): 345–51.

10.  Matias, Denise Margaret S. et al. 2017. “A Review of Ecosystem Service Benefits from Wild Bees across Social Contexts.” Ambio 46(4): 456–67.

11.  Ollerton J, Winfree R, Tarrant S: How many flowering plants are pollinated by animals? Oikos 2011, 120(3):321-326.

12.  Rogers, Shelley R., David R. Tarpy, and Hannah J. Burrack. 2014. “Bee Species Diversity Enhances Productivity and Stability in a Perennial Crop.” PLOS ONE 9(5): e97307.

13.  Szabo, Nora D. et al. 2012. “Do Pathogen Spillover, Pesticide Use, or Habitat Loss Explain Recent North American Bumblebee Declines?” Conservation Letters 5(3): 232–39.

14.  “The IUCN Red List of Threatened Species.” IUCN Red List of Threatened Species. https://www.iucnredlist.org/en (February 20, 2020).

15.  “What Are Pollinators and Why Do We Need Them? (Center for Pollinator Research).” Center for Pollinator Research (Penn State University). https://ento.psu.edu/pollinators/resources-and-outreach/what-are-pollinators-and-why-do-we-need-them (February 21, 2020).

16.  “Why bees matter.” Food and Agriculture Organization of the United Nations. 2018. http://www.fao.org/3/I9527EN/i9527en.PDF

17.  Wilson, Joseph S., Matthew L. Forister, and Olivia Messinger Carril. 2017. “Interest Exceeds Understanding in Public Support of Bee Conservation.” Frontiers in Ecology and the Environment 15(8): 460–66.

The “man” in mangroves: How does the Anthropocene impact biodiversity in these ecosystems?

 *This post is by Nina Adamo, a student in Marc's 'Causes and COnsequences of Diversity' class.

Mangroves are among the most biologically important forest ecosystems on Earth, found in the intertidal zone between land and sea along tropical and subtropical coasts around the world.⁷ Mangrove ecosystems provide habitat for a wide range of terrestrial as well as aquatic organisms including plants, fish, mollusks, birds, reptiles, and crustaceans, among many others.¹

Mangroves also serve as nursery habitats for various fish and crab species found in coastal regions, as mangroves provide high abundances of food and shelter for developing wildlife living in coastal regions.⁷ Since many species use mangroves as nursery grounds, fish diversity and abundance in neighbouring coastal ecosystems has been positively linked to the proximity of mangrove areas, suggesting that mangrove habitat is critical in supporting biodiversity in surrounding coastal ecosystems.⁵

Figure 1: Many species such as fish and crustaceans use mangroves as a nursery site for their young, where shelter from predators and food is abundant.⁹

Along with supporting a wide range of biodiversity along coastal ecosystems, mangroves also provide many essential ecosystem services to humans. Some of these societal benefits include natural resources such as fish and timber, coastal protection from storms, and assisting in mitigating climate change by removing carbon dioxide from the atmosphere and storing it.¹¹

Despite the critical role mangroves play in supporting coastal biodiversity and providing ecosystem services to society, mangroves have been disappearing globally at an alarming rate of 1-2% per year due to anthropogenic activities and accelerated global climate change.⁴ The main threats to these ecosystems are rising sea levels causing coastal erosion, environmental condition changes due to climate change, land-use changes, deforestation, and overexploitation of natural resources.⁴ This has led to the loss of about 50% of mangrove coverage across the globe since 1950.¹⁰

In recent years, there have been a great number of studies that have explored the impacts of anthropogenic activities and climate change on the biodiversity of vegetation, benthic meiofauna, and benthic fauna found in mangrove ecosystems.

Figure 2: A stilt mangrove tree in a mangrove forest coastal ecosystem on an island in East Kalimantan, Indonesia.⁸

In the Sundarbans, which is the world’s largest remaining natural mangrove ecosystem located on the border of Bangladesh and India, there has been a homogenization of tree species composition over the span of 28 years from the 1980s to the 2010s.¹⁰ In other words, the largest remaining mangrove ecosystem has experienced a loss in community biodiversity of mangrove plant species over time due to anthropogenic activities and the environmental impact of climate change.

The loss of biodiversity in ecosystems is a crucial issue because higher biodiversity in most ecosystems typically leads to higher ecosystem functioning, so if biodiversity is lost through stressors such as habitat loss or extreme environmental conditions such as those produced through global climate change, it could have severe impacts on the diversity of an ecosystem and hence the functioning of the ecosystem as a whole.²

The biodiversity of benthic meiofauna, which are very small invertebrates that live in the bottom of aquatic mangrove ecosystems, are also negatively impacted by anthropogenic disturbances. In a comparison study of disturbed and undisturbed mangrove areas, disturbed areas displayed a 20% loss of benthic meiofauna biodiversity compared to undisturbed mangrove areas.² Since many juvenile fish species that use mangrove ecosystems as nursery grounds rely heavily on meiofauna for food, this loss of biodiversity through anthropogenic causes could cause a reduction in ecosystem functioning not only within mangrove communities but in surrounding coastal ecosystems as well.²

A similar observation is also found with the biodiversity of benthic fauna in mangrove ecosystems in the Philippines, where protected mangrove ecosystems have significantly higher diversity and abundance of crab species than reforested mangrove ecosystems that have been disturbed by humans.¹ This suggests that environmental factors influenced by climate change and human influences in mangrove ecosystems can have a negative impact on the biodiversity of benthic fauna, one of the most dominant groups in these systems, which could impair the overall functioning of the ecosystem.¹

With the increasing loss of mangrove habitat and the biodiversity within it across the globe due to anthropogenic activities and climate change, it is essential that humans intervene with utilizing other paradigms such as the flagship species paradigm to increase mangrove conservation and policies to protect mangrove habitat,¹¹ well-researched and well-managed mangrove planting restoration,⁶ and more research on innovative manmade artificial mangroves that may help to restore these ecosystems.³

Figure 3: Locations of the various megafauna found in mangroves (locations of mangrove areas shown in green) around the globe, with the orange representing terrestrial and the blue representing aquatic megafauna. Some examples of megafauna found in mangroves (from top-left to bottom-left in a clockwise direction) include the Key deer, Manatee, Sailfin lizard, Sawfish, Three-toed sloth, Spotted deer, Bengal tiger, Otter, Green turtle, Crocodile, and the Proboscis monkey.¹¹

The focus of much of the recent research on mangrove conservation has utilized an ecosystem services approach, where the benefits that mangroves provide to humans is stressed as an incentive for conservation.¹¹ For this reason, most of the research has been focused on smaller benthic invertebrates such as crabs and shrimp, rather than larger charismatic megafauna that are found in mangroves around the world such as sloths, Bengal tigers, green turtles, and proboscis monkeys.¹¹

Conservation awareness of mangrove ecosystems could be improved by using the flagship species paradigm which uses larger charismatic species found in mangrove ecosystems in marketing campaigns that would protect the entire ecosystem in which they are found. Since charismatic megafauna have been observed in mangrove habitats across the globe, using the flagship species paradigm in conjunction with the ecosystem services paradigm could increase public awareness of the threats facing these extremely diverse and productive ecosystems.¹¹

Conserving mangrove ecosystems around the world is important as these ecosystems provide ecosystem services to human society and play a critical role in supporting biodiversity within mangrove systems and in neighbouring coastal systems. With the increasing threat of anthropogenic activities and global climate change, the conservation and protection of mangroves is essential to reduce the decline in ecosystem functioning and biodiversity in these ecologically important ecosystems that many animals and humans alike rely on in order to live productive and successful lives.

References

1.     Bandibas, M. B., & Hilomen, V. V. (2016). Crab biodiversity under different management schemes of mangrove ecosystems. Global Journal of Environmental Science and Management, 2(1), 19–30. https://doi.org/10.7508/gjesm.2016.01.003

2.     Carugati, L., Gatto, B., Rastelli, E., Lo Martire, M., Coral, C., Greco, S., & Danovaro, R. (2018). Impact of mangrove forests degradation on biodiversity and ecosystem functioning. Scientific Reports, 8(1), 1–11. https://doi.org/10.1038/s41598-018-31683-0

3.     Florida Atlantic University. (2018). Humanmade mangroves could get to the “root” of the problem for threats to coastal areas. ScienceDaily. Retrieved February 20, 2020, from https://www.sciencedaily.com/releases/2018/08/180829115627.htm

4.     Hapsari, K. A., Jennerjahn, T. C., Lukas, M. C., Karius, V., & Behling, H. (2019). Intertwined effects of climate and land use change on environmental dynamics and carbon accumulation in a mangrove-fringed coastal lagoon in Java, Indonesia. Global Change Biology. https://doi.org/10.1111/gcb.14926

5.     Henderson, C. J., Gilby, B. L., Schlacher, T. A., Connolly, R. M., Sheaves, M., Flint, N., Borland, H. P., & Olds, A. D. (2019). Contrasting effects of mangroves and armoured shorelines on fish assemblages in tropical estuarine seascapes. Ices Journal of Marine Science, 76(4), 1052–1061. https://doi.org/10.1093/icesjms/fsz007

6.     Kodikara, K. A. S., Mukherjee, N., Jayatissa, L. P., Dahdouh‐Guebas, F., & Koedam, N. (2017). Have mangrove restoration projects worked? An in-depth study in Sri Lanka. Restoration Ecology, 25(5), 705–716. https://doi.org/10.1111/rec.12492

7.     Nagelkerken, I., Blaber, S. J. M., Bouillon, S., Green, P., Haywood, M., Kirton, L. G., Meynecke, J.-O., Pawlik, J., Penrose, H. M., Sasekumar, A., & Somerfield, P. J. (2008). The habitat function of mangroves for terrestrial and marine fauna: A review. Aquatic Botany, 89(2), 155–185. https://doi.org/10.1016/j.aquabot.2007.12.007

8.     Rante, A. (2019, December 12). A stilt mangrove tree in a protected area on Semama Island in East Kalimantan. Supertrees: Meet Indonesia’s mangrove, the tree that stores carbon. [Image].Vox. Retrieved February 20, 2020 from https://www.vox.com/2019/12/12/21009910/climate-change-indonesia-mangroves-palm-oil-shrimp-negative-emissions-blue-carbon

9.     Rante, A. (2019, December 12). In the water lapping at mangrove roots, young fish and plankton take refuge from predators. Supertrees: Meet Indonesia’s mangrove, the tree that stores carbon. [Image].Vox. Retrieved February 20, 2020 from https://www.vox.com/2019/12/12/21009910/climate-change-indonesia-mangroves-palm-oil-shrimp-negative-emissions-blue-carbon

10.  Sarker, S. K., Matthiopoulos, J., Mitchell, S. N., Ahmed, Z. U., Mamun, Md. B. A., & Reeve, R. (2019). 1980s–2010s: The world’s largest mangrove ecosystem is becoming homogeneous. Biological Conservation, 236, 79–91. https://doi.org/10.1016/j.biocon.2019.05.011

11.  Thompson, B. S., & Rog, S. M. (2019). Beyond ecosystem services: Using charismatic megafauna as flagship species for mangrove forest conservation. Environmental Science & Policy, 102, 9–17. https://doi.org/10.1016/j.envsci.2019.09.009