EEB Seminar: October 18th

This week we welcome our own Adam Groulx. 

Nesting aggregation as a predictor of brood parasitism in mason bees (Osmia spp.)

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Identifying forces that affect population dynamics can allow us to better understand the distribution and abundance of animals. Mason bees are important pollinators for agricultural systems and are vulnerable to exploitation by brood parasites, such as kleptoparasitic wasps. High levels of nesting density have the potential to increase rates of brood parasitism by attracting parasites to areas with aggregations of nests. I conducted a field study at the Rocky Mountain Biological Laboratory in Colorado, USA to assess whether mason bees suffered increased brood parasitism as the size of nesting aggregations increased. I discuss the results of this study and their implications for mason bee populations in both natural and agricultural systems.

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EEB Seminar: October 11th

This week we welcome our own Matt Macpherson and Amelia Cox.

Our Hurting Herps: An update on the conservation of Ontario’s amphibian and reptiles

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Long-term study of an avian aerial insectivore points to climate change as a driver of decline

 

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Ontario is home to a diverse, albeit small array of reptile and amphibian species. However, like other species of herpetofauna around the globe, a large proportion of them are at risk of extinction. In this presentation, I will be going over the natural history, reasons for population declines, and current conservation strategies for these beautiful and fascinating animals.


Avian aerial insectivores, birds that forage on flying insects, are facing dire population declines. The primary commonality among these birds is that they forage on flying insects, suggesting that diet has exposed these birds to environmental challenges that cause their decline, but it has been unclear how. Using data from a tree swallow (Tachycineta bicolor) population that has been continuously monitored from 1975-2017, I investigated demographic and environmental causes of population decline. I suggest that tree swallows and other avian aerial insectivores be added to the growing list of species threatened by climate change

EEB Seminar: October 4th

This week we welcome Karl Grieshop. 

Broad evolutionary implications for sex-specific selection

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Males and females of sexually reproducing species must use largely the same genome to develop into very different organisms that accrue fitness in fundamentally different ways. Inevitably, some of the loci underlying fitness experience sexually antagonistic (SA) selection, where alternative alleles have opposite fitness effects in males versus females. Under some conditions, SA selection can maintain stable polymorphisms for fitness, and explain a large proportion of the heritable genetic variance in fitness that we observe in nature. One of these conditions is sex-specific dominance (where the allele that benefits a given sex is also dominant in that sex), which is theoretically inevitable for loci under SA selection, but empirical tests are nearly lacking. I will present evidence for sex-specific dominance of the SA genetic variation for fitness being a strong and widespread phenomenon throughout the genome of a well-characterized seed beetle population. I will then walk through a series of studies on that same population, showing how SA genetic variation influences life history trait variation, population growth, adaptation, inbreeding depression, and mutation load. Results will be discussed in terms of their implications for our understanding of evolution, wildlife management and public health.

EEB Seminar: September 27

This week we welcome David Punzalan. 

The big and small: ambush bugs and the limits to micro- and macroevolution

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The abundance of biological diversity is a testament to the role of natural selection in evolutionary processes.  Yet, empirical evidence suggests processes that must restrict or constrain evolution.  Quantitative genetics provides powerful tools to describe the factors that drive—but also potentially limit—change in the immediate term, but how useful are contemporary estimates for understanding and predicting patterns in the distant past and future?  Inspired by a group of non-model insects, my work attempts to find mechanistic explanations for local (i.e. species-specific) phenomena, while addressing broad, and often puzzling patterns that are at the heart of the unification of micro- and macroevolution.

EEB Seminar: September 20th

This week we welcome our own Bob Montgomerie.

The enduring enchantment of birds’ eggs

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Birds’ eggs are some of the most variable and beautiful natural objects, but only recently has there been any attempt to explain that variation. In this talk I will summarize the history of egg collecting and explore some recent research on variation in the shape and colour of avian eggs, including our own experimental and comparative studies of robins, alcids and penguins.

EEB SEMINAR: SEPTEMBER 13

Welcome back! This week we are pleased to welcome our own Paul Martin.

Life in the city:

Opportunities and challenges for interacting species

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Urbanization represents an extreme transformation of more natural systems. Populations of most species decline or disappear with urbanization, and yet some species persist and even thrive incities. What determines which species persist or thrive in urban habitats? Direct competitive interactions among species can influence their distributions and resource use, particularly along gradients of environmental challenge. Given the challenges of urbanization, similar interactions may be important for determining which species persist or thrive in cities; however, their role remains poorly understood. In this talk, I will present the results of my collaborative work with Fran Bonier that uses a large, global dataset to test among three alternative hypotheses for how direct competitive interactions and behavioral dominance may influence the breeding occurrence of birds in cities.

We found evidence to support the Competitive Interference Hypothesis: behaviorally dominant species were more widespread in urban habitats than closely-related subordinate species, but only in taxa that thrive in urban environments (hereafter, urban-adapted), and only when dominant and subordinate species overlapped their geographic ranges. This result was evident across diverse phylogenetic groups, but varied significantly with a country’s level of economic development. Urban-adapted, dominant species were more widespread than closely-related subordinate species in cities in developed, but not developing, countries; countries in economic transition showed an intermediate pattern. Our results provide evidence that competitive interactions broadly influence species responses to urbanization, and that these interactions have asymmetric effects on subordinate species that otherwise could be widespread in urban environments. Results further suggest that economic development might accentuate the consequences of competitive interactions, thereby reducing local diversity in cities.

The EEB Seminars run weekly, on Thursdays, in the EEB Lounge of the BioSciences Complex, Room 4338, from 12:30-1:30pm.

EEB SEMINAR: APRIL 12

This week we are pleased to welcome our own Yihan Wu.

Reconstructing parallel clines in flowering phenology from natural history collections of Lythrum salicaria

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Rapid shifts in phenology during biological invasions can increase survival and reproduction of invasive species, contributing to their spread and impact. However, it is not clear how quickly invasive populations can tune their phenology in response to local environmental cues. Global herbarium specimens represent spatial and temporal snapshots of phenology that could be analyzed for environmental tuning by correlating phenological development to local climatic factors. In this study, inflorescence measurements of herbarium specimens were combined with historical weather data to investigate modern and historic clines in flowering phenology throughout the North American distribution of the invasive plant Lythrum salicaria (purple loosestrife).

Inflorescence morphology (i.e. buds, flowers, fruits) was characterized from 3,427 herbarium specimens and interpolated the season length and growing-degree-days from 6,303 unique weather stations by inverse distance weighing. A flowering time index (FTI) was calculated from phenology measurements, which corrected for variation in collection date and local growing conditions.

FTI of herbarium specimens was strongly correlated with genetic differences in time to first flower measured in four common garden experiments. Using a non-linear least squares model, the effects of interpolated season length and time since invasion were compared throughout the North American range. Specimens collected from older populations in locations with short growing seasons reached maturity faster than specimens collected from early populations with short growing seasons. Herbarium specimens can be a valuable resource in reconstructing historical phenological changes due to rapid adaptation.

The EEB Seminars run weekly, on Thursdays, in the EEB Lounge of the BioSciences Complex, Room 4338, from 12:30-1:30pm.