Evolution Flashcards
(41 cards)
Define Species
A species consists of members of interbreeding groups or populations that are reproductively isolated from other groups and evolve independently.
What are Reproductive Isolating Mechanisms?
Any behavioural, structural, or biochemical trait that prevents individuals of different species from reproducing successfully together.
What are the three reproductive isolating mechanisms?
Habitat Isolation, Temporal Isolation, Behavioural Isolation
What is Habitat Isolation?
Ground hogs live in different habitats. Woodchucks live in fields at lower elevations while others live in alpine meadows at higher elevation in the same region.
What is Temporal Isolation?
Similar plant species bloom at
different times of the day or in
different seasons.
What is Behavioural Isolation?
Each species may use different signals for attracting mates. The male jumping spider jumps to attract the female. Other similar female spiders do not respond to the jumping.
What are two prezygotic mechanisms that restrict fertilization?
Mechanical Isolation, Gametic Isolation.
Define Mechanical Isolation and give an example
The male and female reproductive parts are not anatomically compatible. Ex- Pollen sacs in a lady’s slipper orchid become attached to an insect, but they are not removed by any other.
Define Gametic Isolation and give an example
The gametes (male and female) will not fuse and create a zygote. Ex- Giant clams release sperm and eggs into open water, gametes recognize one another by molecular markers.
What are Postzygotic Mechanisms?
These mechanisms prevent the hybrid organism from developing into a healthy, fertile adult.
What are the three postzygotic isolating mechanisms?
Hybrid Breakdown, Hybrid Inviability, Hybrid Sterility
What is the result of Hybrid Breakdown?
First-generation hybrids are viable and
fertile. Their offspring tend to be weak,
or sterile.
What is the result of Hybrid Inviability?
Hybrid offspring do not live very long.
What is the result of Hybrid Sterility?
Offspring of genetically dissimilar parents are likely to be strong but sterile ( mule – donkey and horse ).
What are the Modes of Speciation?
Allopatric Speciation, Sympatric Speciation
What is Allopatric Speciation?
The creation of new species due to a physical barrier
( river, ocean, canyon, highways, dams, lava flows, ocean levels rising turning peninsulas into islands). The populations begin to diverge (due to genetic drift/or gene flow).
What is Sympatric Speciation?
Populations that split into two separate gene pools and remain in the same geographic area. Most common in plants. This can occur due to chromosomal changes (in plants) and non-random mating (in animals) that alter gene flow.
What are factors that affect the Change of Allele frequency?
Mutations, Gene Flow (migration), Non-random mating, Genetic Drift, Natural Selection
What are Mutations?
Random changes in the sequence of DNA through un-repaired changes, chromosome breakage and rejoining.
What is Gene Flow (migration)?
The movement of alleles from one population to another through the movement of individuals or gametes (sex cells).
What is Non-random Mating?
This occurs when mates are selected over others.
What is Genetic Drift?
Changes the allele frequency as a result of chance; such changes are much more pronounced in small populations.
What are some evidence of evolution?
Fossil Record, Biogeography, Anatomy, Embryology, DNA
What are fossils and what do they do?
Fossils are any preserved remains or traces of an organism or it’s activity ( usually from hardened body parts such as bone ) They are evidence for the History of Life. Fossils discovered in sedimentary rock have provided scientists with a glimpse into the past.
