Kahrl Publishes Book Chapter and Co-authors Two Papers

Kahrl’s book chapter titled ‘Fertilization modes across animals’ is set to be released in November as part of the Encyclopedia of Reproduction 3rd edition. In this, Kahrl explores the diversity of fertilization modes across all animals. Species are often categorized as being internal fertilizers, where fertilization takes place inside the female’s reproductive tract (like in humans) or as external fertilizers, where sperm and eggs meet outside the body (like fish and frogs). 

However, across the animal tree of life there are hundreds of different ways that animals fertilize eggs that aren’t well-represented by these two categories. This chapter highlights this diversity and especially a large category of species called spermcasters, which are often overlooked but represent many aquatic invertebrates.

Kahrl’s two co-authored papers stem from her Ph.D, work on a population of brown anole lizards in Florida. The first paper led by Anthony Gilbert and published in the journal Evolution, titled “The landscape of natural selection during early population establishment in an invasive lizard,” examines how the make-up (density, and sex ratio) of a founding population can alter selection on the population. Gilbert et al. found that populations with high density and more females than males had stronger selection on juveniles. This suggests that variation in the landscape can result in variation in selection across a landscape, potentially resulting in novel evolutionary trajectories during population establishment.

The second paper led by Ashlyn Crain, published in the Journal of Evolutionary Biology titled “Parental age effects on offspring fitness in a wild population of a short-lived reptile,” examined whether parental age affects offspring quality. To ask this they examined age of parents and offspring survival and reproduction across five years of mark-recapture data in an island population of brown anoles. Despite theory that older parents should produce offspring that are in worse condition, their study found no evidence of maternal or paternal age on offspring. This paper adds to the growing body of evidence that negative effects of parental age may not be as prevalent as previously thought.