Species and Speciation Flashcards
Biology species concept
population where individuals can make fertile, healthy babies
limitations: can’t use it on all prokaryotes and asexual organisms
reproductive isolation
biological barrier that stops two different species from mating or from making healthy, fertile babies
Two types of reproductive barriers
- prezygotic barriers
2. postzygotic barriers
- prezygotic barriers
- habitat isolation
- temporal isolation
- behavioural isolation
- mechanical isolation
- gametic isolation
- habitat isolation
species live in same environment but occupy different parts of it
- temporal (time) isolation
make babies at different times of day, different seasons, different years
- behavioural isolation
species attract their mates differently from one another
- mechanical isolation
will try to mate but can’t because of their morphology
- gametic isolation
sperm of one species can’t fertilise the other. sperm could get destroyed in female tract
Postzygotic barriers
- reduced hybrid viability
- reduced hybrid fertility
- hybrid breakdown
- reduced hybrid viability
even though mating was successful the hybrid might die while developing or won’t develop properly
- reduced hyrbrid fertility
hybrid won’t be infertile
genes can’t flow between species
can’t make normal gametes
- hybrid breakdown
hybrid can be fertile and healthy but when it tries to reproduce with mate from one of the parent species it can’t because it will make unhealthy and infertile babies
Morphological species concept
establish species according to their structural features or body shape
limitation: which structure would you choose? you’d have to agree on one
ecological species concept
establishing species according to their ecological niche
you can use it on asexual and sexual organisms
focuses on disruptive selection
Speciation can happen two ways
- allopatric speciation
2. sympatric speciation
allopatric speciation
population is separated by geographic barrier
gene flow can’t happen anymore
because of that there will be reproductive isolation instead of adaptive selection
when population is separated populations evolve independently by
1. natural selection
2. point mutation
3. genetic drift
sympatric speciation
population that’s not divided by a physical barrier but by biological ones
if gene flow is reduced it’s because of :
1. polyploidy
when error occurs during cell division = extra set of chromosomes
2. sexual selection
3. habitat differentiation
- polyploidy
- autopolyploidy
more than 2 sets of chromosomes from 1 species - allopolyploidy
can mate but can’t make babies with either parent species
- sexual selection
females choose males
mates will have different colours
- habitat differentiation
new ecological niche could appear
Hybrid zones
space where 2 different species mate
species with incomplete reproductive barriers mate
