Bio 4H ch24 (exam 3)

species (biological species concept)

group of organisms which interbreed successfully in nature, or potentially could do so

speciation

processes which give rise to new species

problem w/ biological species concept

asexual species (can only differentiate w/appearance genetics)

fossil species (if they can mate, but already tea,d no dna bc rocks, not all 100%, and naming based on appearance (not the best)

naturally occurring spatial separation

geographical barrier

splits species into two population (river/stream, 2 ponds and dirt splitting btwn) evolve separately

reproductive barrier

if evolves, then two population can’t and will not interbreed even if geographic barrier is removed, one species has become two

why do so many island chains have so many species

separated by water

sympatric speciation

autopolyploidy & allopolyploidy

habitat isolation

2 species occupy diff habitats w'/in same area, may encounter each other rarely

temporal isolation

species breed during diff time of day, season, year, can’t mix gametes

behavioral isolation

courtship ritual attract/mate & other unique behavior specific to species, effective reproductive barriers, even brown closely related species

mechanical isolation

mating attempted, morphological diff, prevented its successful completion

gametic isolation

sperm can’t fertilize egg of another species

post zygotic hybrid barriers

reduce hybrid viability, fertility, hybrid breakdown

reduced hybrid viability

genes of diff parent species interact in ways that impair the hybrid’s development or survival in its environment

reduced hybrid fertility

may be sterile if chromosomes of two parent species differ in # /structure, meiosis in hybrids can’t make normal gametes. infertile hybrids no offspring when mate w/parent species, no free gene flow btwn species

hybrid breakdown

first gen hybrids viable/fertile, but when mate each other/parent species, offspring of next gen feeble/sterile