speciation Flashcards
L15
What is speciation
group of individuals that can interbreed and produce VIABLE (fertile offspring)
what are cryptic species
species that genetically distinct but look similar
whats ring species
connected population can interbreed locally but not at the extremes
what are hybrids
cross-species offspring can somehow be fertile (hippo mating with a lion)
morphological
focuses on body shape/ observable traits
useful for fossils and unknown genetics
phylogenetic
focuses on evolutionary history/ genetic history
useful for revealing cryptic species
ecological
role/niche in ecosystem
useful fro ecologically distinct species in similar areas
how do new species occur
speciation starts when gene flow stops between population
isolation allows genetic differences to accumulate to new species.
whats pre zygotic, what are the barriers
prevents fertilization
act befroe a zygote
Geographical
Ecological
Temporal
Behaviour
Mechanical
Gametes
ecological / habitat isolation
same area, diff habitat
one prefers trees, other soil
temporal
different mating times
one mates in spring or in years
behaviour
diff mating signals
fireflies w their flashing signals
mechanical
physical incompatible, mating parts don’t fit
gametic
sperm and egg don’t fuse,
Whats Post-Zygotic Barriers and what are the types
they kick in after fertilization
Hybrid inviability
Hybrid sterility
Hybrid breakdown
Hybrid inviability
embryo dies early
Hybrid sterility
offspring survives but can’t reproduce
horse + donkey = strong but can’t reproduce
Hybrid breakdown
grand kids of hybrids are weak or infertile
what are the 3 types of speciation and how do they occur
allopatric
sympatric
parapatric
what’s allopatric
physical barrier separates population like rivers, canyons, glacier divides
whats sympatric
same area, but behaviour or ecological separation
whats parapatric
adjacent but limited gene flow; hybrid zones
when population diverge
how fast does speciation happen
gradualism:
- evolution is slow and steady
- small changes build up over time
punctuated equilibrium
- long periods of no change –> short, rapid bursts of evolution
-often triggered by environmental changes or new niches
what happens if speciation fails
reinforcement - hybrids are less fit, species stay separate
fusion- species merge again
stability - hybrids persist long-term, stable hybrid zones form
