Evolution- 4.3 Species Flashcards
3.1- Species, 3.2- Reproductive Isolation, 3.3- Genetic Variation, 3.4- Gene Pools, 3.5- Natural Selection, 3.6- Genetic Drift
What is the main criterion used to define a species in organisms that reproduce sexually?
A species is defined by the ability of its members to interbreed and produce fertile offspring.
What is a hybrid in terms of species reproduction?
A hybrid is the offspring produced through the sexual reproduction of two different species.
How are species that reproduce asexually, like bacteria, defined since they cannot interbreed?
Species that reproduce asexually cannot be classified by interbreeding criteria. They are instead defined by other criteria, such as morphological or biochemical similarity.
What role does morphological similarity play in defining a species?
Members of a species often share similarities in appearance, but morphological similarity alone does not necessarily define a species.
What biochemical criteria are used to help define a species?
Members of the same species have greater similarity in their DNA base sequence and amino acid sequence than members of different species.
What is meant by members of a species sharing a common gene pool?
Members of the same species share a common gene pool, meaning they can interbreed and exchange genes, while different species are reproductively isolated and have separate gene pools.
Why can’t the ability to interbreed be used to define asexual species like bacteria?
Asexual species, like bacteria, reproduce through binary fission, so they do not interbreed, requiring different criteria for species classification
What are reproductive isolating mechanisms?
Barriers that prevent two populations from interbreeding to produce fertile offspring, maintaining distinct species.
What are pre-zygotic mechanisms?
Mechanisms that prevent the formation of a zygote by stopping fertilization before it occurs.
What is temporal isolation?
Temporal isolation occurs when species reproduce at different times, preventing interbreeding.
What is behavioral isolation?
Behavioral isolation is when differences in mating behaviors prevent mate recognition between males and females of different species.
What is mechanical isolation?
Mechanical isolation occurs when anatomical differences between species prevent successful mating.
What is gamete isolation?
Gamete isolation occurs when gametes from two species come into contact but cannot fuse, or the female reproductive tract is unsuitable for the male gametes.
What are post-zygotic mechanisms?
Mechanisms that prevent hybrids from developing into fertile adults after fertilization.
What is hybrid inviability?
Hybrid inviability occurs when hybrids fail to develop to reproductive maturity.
What is hybrid sterility?
Hybrid sterility occurs when hybrids develop into adults but cannot reproduce due to issues like producing no gametes or having incompatible chromosomes.
What are the sources of genetic variation during gamete production in sexually reproducing species?
Genetic variation arises from crossing over during prophase I, and independent assortment during metaphase I, both contributing to new combinations of genes.
How does random fertilization contribute to genetic variation?
Random fertilization occurs when the fusion of sperm and egg is random, creating unique combinations of genetic material in offspring.
How does mutation contribute to genetic variation?
Mutation introduces new variations or changes in DNA base sequences, leading to genetic diversity in a population.
What is a gene pool?
A gene pool is the total sum of all genetic information within an interbreeding population.
Why is a large gene pool important for survival?
A large gene pool provides genetic diversity, increasing the population’s ability to survive environmental changes and reducing the risk of extinction.
How does natural selection lead to evolution?
Natural selection causes changes in allele frequency over generations, favoring traits that offer a survival advantage, resulting in evolutionary changes.
What determines which traits are passed on through natural selection?
Traits that provide an advantage under selective pressures are more likely to be passed on to future generations, increasing in frequency within the gene pool.
What is genetic drift?
Genetic drift is the random change in allele frequencies within a population due to chance events, not environmental selection pressures.
How does genetic drift affect smaller populations?
Genetic drift has a more pronounced effect on smaller populations, reducing genetic diversity and increasing the risk of extinction.
What are examples of events that can cause genetic drift?
Events like bushfires, hunting, hurricanes, and flooding can cause genetic drift by reducing the population size and altering allele frequencies.
