Tag Archives: breeding

Adapt or Die

Mandt’s Black Guillemont (Image Credit: Óskar Elías Sigurðsson, CC-BY 2.0, Image Cropped)

Phenotypic plasticity or evolutionary change? An examination of the phenological response of an arctic seabird to climate change (2019) Sauve et al., Functional Ecology, https://doi.org/10.1111/1365-2435.13406

The Crux

If you’re here on Ecology for the Masses, then you know that climate change is not only real but is causing all kinds of problems for organisms the world over. One of the things that climate change is doing is altering seasonality, the time of year in which a given season will take place. For example, where I live in the US, it is normally cold at this time of year, but as I write this it is 60F/16C, much warmer than it should be despite it almost being winter. These changes can affect when organisms start their seasonal breeding, but how these breeding events change is not always the same.

Some changes are due to evolution, or the change in a population’s gene frequencies over time. As mutations and selection take place, a given population may have some traits or behaviors selected for over others. Another way that these changes can happen is via plasticity, which is a change induced by the environment, but without changing the gene frequencies (See Did You Know? for more information). The authors of today’s paper wanted to know if the change in breeding dates of a colony of seabirds (Mandt’s black guillemont, Cepphus grylle mandtii) was due to evolution or plasticity.

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Hibernating and Mating

Male echidna must stay on the move to find females before other males do (Image Credit: JKMelville, CC BY-SA 3.0, Image Cropped)
Energetics meets sexual conflict: The phenology of hibernation in Tasmanian echidnas (2019) Nicol et al., Functional Ecology, https://doi.org/10.1111/1365-2435.13447

The Crux

Seasonality (i.e. the change in season throughout the course of the year) has huge impacts on the lives of animals that live in temperate habitats. The change in season is associated with changes in food availability, and as such some animals hibernate through the tough winter months and wait until the food and warmer weather comes back. Another aspect of an animal’s life impacted by seasonality is the breeding season, as animals living in temperate habitats must time their breeding around the winter months, while animals in tropical habitats can breed year-round.

Within a single species the timing of hibernation may be affected by the different energetic and reproductive needs of the different sexes. Females may start hibernating later than males because they have to store more energy for their pregnancy and lactation, while males may emerge from hibernation earlier than females to establish territories and increase their chance of mating. Tasmanian echidnas (Tachyglossus aculeatus) exhibit markedly different hibernation patterns among the sexes, and the authors of today’s study wanted to know if these differences are due to where they live or whether they are inherent to the species itself.

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Too Many Fish on the Sea Floor

When fish like this sand goby aggregate, the density of their nests can often have a big impact on their success
When fish like this goby aggregate, the density of their nests can often have a big impact on their success (Image Credit: Laszlo Ilyes, CC BY 2.0, Image Cropped)
Spatial and temporal patterns of nest distribution influence sexual selection in a marine fish (2018) Wong et al., Oikos, doi: 10.1111/oik.05058

The Crux

When we monitor the fluctuations of a population, we often look at vital rates, a huge part of which is reproductive success. The success that males have in siring offspring can be hugely influenced by the density of a population, particularly when it comes to a breeding ground.

Larger males will often outcompete smaller males on such grounds, however in many species these males will often reach reproductive limits, at which point smaller males can benefit. Smaller males may also fare better in less dense populations, where females lack other individuals to compare them to. Our study today looks at variations in reproductive success of a nest-breeding fish species over two levels of density.

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