How and why are males and females of the same species so different? 

 Males and females of the same species share most of the same genes. However, despite their shared genome, the traits and underlying genes that make a successful male are frequently not the same as those that make a successful female. This sets up a genomic and evolutionary tug-of-war between the sexes known as intralocus sexual conflict as natural and sexual selection pull males and females in different evolutionary directions. My current research is focused on this sexual conflict and ultimately on the larger questions it poses in evolutionary biology.

My ongoing work uses wild populations of brown anole lizards (Anolis sagrei) because of their extreme sex differences. I use islands as living laboratories to study evolutionary processes in the wild.

The relationship between a trait and fitness is often very different for males and females. Natural selection can pull the genome in different directions for each sex.

The relationship between a trait and fitness is often very different for males and females. Natural selection can pull the genome in different directions for each sex.

Intralocus sexual conflict

I am using mark-recapture methods and genetic assignment of parentage with GT-Seq to track  the survival and reproductive success of more than 4,500 individual lizards across 3 generations in an island population of brown anole lizards. This will allow for a large scale test of many of the fundamental predictions of intralocus sexual conflict theory. Do families with high fitness males have low fitness daughters?

 

 

Individuals of both sexes showed an acute increase in stress hormones while engaged in mating behavior (amplexus). 

Individuals of both sexes showed an acute increase in stress hormones while engaged in mating behavior (amplexus). 

Comparing stress hormones in both sexes

Hormones play key roles in mediating the tradeoff between survival and reproduction. Stress hormones can inhibit reproduction and improve chances of survival during periods of stress. However, stress hormones can also be associated with successfully engaging in energetically costly reproductive behaviors. Our work found an acute increase in the stress hormone, Cortocosterone, during courtship for both male and female red spotted newts.

Males and females similarly had more body fat and fewer parasites after reproduction was surgically eliminated.

Males and females similarly had more body fat and fewer parasites after reproduction was surgically eliminated.

Costs of reproduction in both sexes 

Sexual selection theory proposes that males suffer increased parasitism as a cost of expressing sexual signals. Life-history theory proposes that females suffer costs because of inherent trade-offs between reproduction and self-maintenance. Surgical elimination of reproduction in both sexes showed that both sexes pay similar costs of reproduction in terms of energy storage and parasitism.

 

 

My high school students showed that female anoles choose nest sites based on moisture and that that choice of nest site has a dramatic effect on offspring survival.

My high school students showed that female anoles choose nest sites based on moisture and that that choice of nest site has a dramatic effect on offspring survival.

Classroom science

I work with teachers and kids to push the limits for classroom science. The work of my students done in a Chicago Public School showed how female anoles choose nest sites and how those choices influence fitness traits.  

I am currently co-advising Evolution Education teacher fellows Brandon Pope and Nick Kiriazis. Pope and his students are testing the effects of predators on the development of sexual dimorphism in mosquitos. Kiriazis and his students are examining repeatable individual differences in the behavior of cockroaches.

 

                                                       Collaborators at Florida field site: Robert Cox. Ariel Kahrl. Brandon Pope. Nick Kiriazis. Albert Chung. Cara Giordano. Cheyene Sams. 

                                                       Collaborators at Florida field site: Robert Cox. Ariel Kahrl. Brandon Pope. Nick Kiriazis. Albert Chung. Cara Giordano. Cheyene Sams.