Week 4 Flashcards
Pros to sexual reproduction
-male parental care
-sexual selection removes bad alleles
-recombination
Cons to sexual reproduction
-Have to make males(2 fold cost)
-may disrupt advantageous combinations of alleles
-could be risky (predation, STDS)
Advantages of having separate sexes
-allows purging of deleterious alleles
-exploit a complex fitness landscape
-decreases inbreeding
Female choice
females may choose mates on the basis of
-physical characteristics
-resources or parental care
What are the causes of sexual selection
female choice, male-male competition, innate biases and sensory exploitation
Honest advertising
attractive physical feature that directly translates to increased fitness
Nuptial gifts
anything a male provides to incise a female to mate with them
ex: sexual cannibalism
What does sexual selection in males being higher than in females cause
higher variation in reproductive success in males vs females, but still produce same amount of offspring on average
Sensory exploitation
preexisting bias before the evolution of that feature
Speciation
occurs when populations accumulate genetic differences that cause reproductive incompatibilities
The biological species concept
assigns individuals to the same species if they actually or potentially interbreed
What is the problem with the BSC
the concept is difficult to apply to natural systems
Examples of Prezygotic isolation
temporal, habitat, behavioral, gametic barrier, mechanical
Examples of Postzygotic isolation
hybrid viability and hybrid sterility
Temporal isolation
populations are isolated because they breed at different times
habitat isolation
populations are isolated because they breed in different habitats
behavioral isolation
populations do not interbreed because their courtship displays differ
Gametic barrier
Matings fail because eggs and sperm are incompatible
Mechanical isolation
Matings fail because male and female genitalia are incompatible
Partial postzygotic isolation
when one gender of a hybrid is sterile and the other is fertile
Hybrid viability
hybrid offspring do not develop normally and die as embryos
hybrid sterility
hybrid offspring mature but are sterile as adults
The Morphospecies Concept
species are distinguished by differences in size shape or other morphological features
-rather subjective
The phylogenetic species Concept
Based on reconstructing the evolutionary history of populations
Species is defined as the smallest monophyletic group on a tree that compares populations
-tends to over diagnose specise
Allopatric Speciation by dispersal
The physical barrier pre-dates the time of speciation
Allopatric speciation by vicariance
the physical barrier causes speciation and therefore is approximately the same age
Geographical distance as a reproduction barrier
allele frequencies are initially evenly distributed and then later become unevenly distributed due to geographical distance
