Biology lecture 2 Flashcards
If more young are born then can survive then…
The young will compete for limited resources
Define Micro-Climate
microclimate is the long-term localized patterns of weather experienced by small communities.
Define Macro-Climate
Macro-Climate is the long term localized patterns of weather experienced globally or on a landscape level
How long does GENE FLOW DISRUPTION take?
The gene flow disruption (isolating mechanisms) take between 4000-40 million years.
What is the CORIOLIS effect?
the coriolis effect is when air and water move clockwise in the Northern hemisphere and counter-clockwise in the southern.
In POST-ZYGOTIC: What are the three reasons why there is reduced hybrid variability?
1) hybrids are steril
2) hybrids don’t live long
3) hybrids have low relative fitness
What is meant by POST-ZYGOTIC?
Post-Zygotic is after fertilization, reduced hybrid variability or fertility.
If there is unequal ability to survive and reproduce then….
If there is reduced ability to survive and reproduce then the population will become accumulated with favorable traits because the carriers will reproduce more than those without.
What is the Founder Effect?
A small group of people reproduces to become a much larger group
Define Pre-Zygotic
Pre-Zygotic prevents fertilization in the first place.
Pre-zygotic
Three isolating mechanisms
1) mechanical isolation
2) behavioral/temporal/habitat isolation
3) gametic isolation
What is mechanical isolation in Pre-zygotic?
mechanical isolation is where “lock and key don’t fit” the sperm cant reach the eggs.
What is Gametic isolation in pre-zygotic?
Sperm and eggs come into contact but no fertilization.
What is Behavioral/Habitat/temporal isolation in pre-zygotic?
They prevent mating from happening in the first place.
Habitat isolation
Habitat isolation is where organisms cant mate because they have different habitats; i.e. land and sea
Temporal Isolation
In temporal isolation species cannot mate because they mate at different times: seasons, hours years.
Behavioral isolation
In behavioral isolation species don’t mate because they have different mating rituals.
In natural selection what are five sources of variation?
1) mutation
2) double allele
3) error during meiosis
4) sexual reproduction
5) gene flow
What are consequences for genetic variation in the Founder Effect
Population size may recover quickly but genetic variation carries on, bad if negative traits are passed down.
What are three consequences of Genetic Drift?
1) Changes in allele frequency is random/unpredictable.
2) Low Genetic Variation makes it difficult to respond too in changing environment
3) Fixation of alleles-bad if they are harmful
How does speciation happen?
When the gene-flow is interrupted and populations become separated and isolated they diverge into two reproductively different species.
Allopatric Speciation
In allopatric speciation subpopulations become geographically isolated-i.e. a river, distance.
Sympathetic Speciation
in sympathetic speciation, while the species may stay in the same area they still become isolated and evolve differently.
Define Genetic Drift
In genetic drift the alleles fluctuate, so certain traits gradually disappear over time, limiting variation. They balance out in large populations but not in smaller ones.
