natural selection x speciation
Cards (16)
- Founder effect
- part of population relocates
- big population to small population
- immigrants establish a new population
- Genetic Bottleneck
- reduction in the diversity of alleles
- cause: random event occurs
- outcome: sudden decrease in size of a population
- Mutation
- change in DNA
- very common
- mostly silent mutation
- most are deleterious or neutral
- necessary for evolution but not sufficient
- does not alter allele frequencies by itself
- cause: mistake during replication; meiosis
- outcome: increases genetic diversity
- Speciation
- genetic isolation --> barrier to genotypes; no gene flow
- genetic divergence, mutation selection and genetic drift in isolated population
- Reproductive isolation: prezygotic, postzygotic, temporal, mechanical, gamete, and habitat isolation
- prezygotic
- before fertilization
- can't mate, don't mate
- behavior is not the same b/w species
- temporal, mechanical, gamete, habitat isolation
- temporal isolation is time-isolation, time of reproduction differs
- mechanical isolation is when structure of two species are different and parts don't physically fit
- Gamete isolation is when sperm and egg don't fit and gametes are not compatible
- Habitat isolation is when species mate and breed in different habitats
- postzygotic isolation
- fertilization occurs but the offspring is not fertile
- postzygotic barriers: hybrid sterility, hybrid inviability
- Hybrid sterility is when the species has different number of chromosomes
- hybrid inviability is when the offspring does not develop normally and dies early
- Biological species concept
- species consist of individuals that can breed and produce fertile offspring
- reproducing isolate individuals represent different species
- Morphospecies concept
- individuals that look different enough are different species
- phenotypes are different = different species
- Phylogenetic concept
- comparing how different or similar population are through ancestry
- phylogeny