Studied by 0 people
Looks like no one added any tags here yet for you.
What is extinction?
When no living individuals of a species remain on Earth, completely wiped out.
What is extirpation?
When a species is no longer found in a specific geographic area but exists in other areas.
What does it mean for a species to be endangered?
A species facing imminent extinction.
What is a threatened species?
A species that is likely to become endangered.
What human activity reduces ecosystem diversity?
deforestation and habitat destruction.
What is habitat loss?
A reduction in the natural environment where a species lives, often due to human activities.
What are invasive species?
Species that have been accidentally or deliberately introduced into non-native areas.
What are examples of overexploitation?
Overfishing Atlantic Cod and overhunting the passenger pigeon.
What do scientific theories encompass?
Broad, fact-supported explanations for phenomena that are widely accepted.
What distinguishes hypotheses from scientific theories?
Hypotheses are proposed explanations for a set of observations that need to be testable and falsifiable.
What is the first step of the scientific method?
Making observations and collecting data.
What is inductive reasoning?
Making generalizations from repeated observations.
What does deductive reasoning entail in the scientific method?
Using generalizations to make specific predictions for testing hypotheses.
What is binomial nomenclature?
A two-part scientific name for a species, consisting of the genus and specific epithet.
What does hierarchical classification involve?
Placing species into broad categories based on their similar structures and functions.
What are the three main domains of life?
Bacteria, Archaea, and Eukarya.
What are phylogenies?
Diagrams that represent evolutionary relationships among species. They use morphological and molecular data to show hypotheses for evolutionary relationships between common ancestors.
What do cladograms represent?
Relationships of organisms based solely on the branching pattern from a common ancestor.
What is a polytomy in phylogenetics?
Branches showing where more than two groups emerged, indicating unresolved patterns of divergence.
What is a sister taxon?
Two descendants from the same node.
What are basal taxon?
Taxa that diverged early from the lineage leading to a group of organisms, representing a more primitive or ancestral form.
What is a monophyletic phylogeny?
The same thing as a clade. A group of organisms that includes an ancestor and all its descendants, forming a complete branch on the tree of life.
What is a paraphyletic phylogeny?
A group that contains a common ancestor but not all the descendants.
What is polyphyletic phylogeny?
A group that includes distantly related taxa but not the common ancestor of all group members.
What are homologous traits?
Traits inherited from a common ancestor that are similar in structure or function across different species. An example is the forelimbs of mammals.
What are analogous traits?
Traits that arise independently in different species due to convergent evolution, serving similar functions but lacking a common ancestor. An example is the streamlined body of marine animals.
What are shared derived traits?
Characteristics that evolved in the most recent common ancestor of a clade that are unique to that group.
What are ancestral traits?
Characteristics that are shared by taxa of a clade and also represented in taxa of earlier clades.
How are phylogenetic trees grouped?
Using shared derived characteristics with the fewest evolutionary changes between lineages.
What does the concept of evolutionary fitness refer to?
The ability of individuals with advantageous traits to survive and reproduce.
Give an example of a selective agent.
Environmental factors that affect the survival and reproduction of populations.
What are the two observations in the theory of evolution by natural selection?
Individuals in a population vary in their genetic diversity and populations produce more offspring than the environment can support>
What are the two inferences in the theory of evolution by natural selection?
Individuals with advantageous inherited traits are more likely to survive and reproduce and the unequal ability of individuals to survive and reproduce will accumulate advantageous traits.
How do selective agents influence natural selection by creating selection pressures?
Selective agents are environmental factors that create challenges for survival, thereby influencing which individuals are favored in reproduction. A consistent agent will become a selection pressure and change change the direction of natural selection.
What is the significance of genetic variation in populations?
It is essential for natural selection and adaptation.
How does genetic variation affect natural selection?
Genetic variation in populations arises randomly but natural selection is not a random process.
What is an example of descent of modification?
The Finch species on the Galapagos islands had distinct differences with beak size variation, adapted for their feeding needs.
What did a drought lead to for the Finch beak size?
Beak depth increased as individuals with larger beaks could open the seeds and could reproduce.
Define a population.
A group of individuals of the same species that live in a specific area and interbreed to produce fertile offspring, sharing a common gene pool. The individuals represent different combinations of alleles drawn from the gene pool.
What evidence is there for evolution?
Direct observations of evolutionary change, homologies, fossil records and biogeography.
What are homologies?
Similarities in traits between different species due to shared ancestry, providing evidence for evolutionary relationships. Examples include morphological homologies, homologous embryonic structures, vestigial structures and molecular homologies.
How do fossils provide evidence for the extinction of species?
Transitional species shows the change in groups overtime while chronological fossils order how groups of taxa appear in fossil records.
What happens when isolated populations undergo adaptive radiation?
They form endemic species that are only found in one area.
How do populations maintain genetic variation?
Through mutations, gene flow, balancing selection, neutral variation and sexual reproduction.
Define neutral variation.
Genetic variation that does not have a selective advantage or disadvantage, it does not affect phenotype.
What is balancing selection?
A type of natural selection that maintains genetic diversity by favouring stable frequencies of multiple alleles in a gene pool. There are multiple types including temporal or spatial variation, heterozygote advantage, frequency or non-frequency dependent selection.
How does temporal/spatial variation maintain genetic variation?
By favoring different alleles in different environments or at different times, allowing for diverse adaptations and environmental conditions change overtime.
What is the heterozygote advantage?
When an organism with two different alleles of a particular gene has a fitness advantage over an organism with identical copies of either allele. It is a result of stabilizing or directional selection.
What is sickle cell disease an example of?
The heterozygote advantage as people with the two alleles have a better resistance to malaria compared to those with normal hemoglobin.
What is frequency-dependent selection?
The fitness of an allele depends on its frequency in the population.
What is negative frequency-dependent selection?
The fitness of an allele declines if it becomes too abundant in the population and selection favours rarer alleles.
What are the three modes of natural selection?
Directional selection, stabilizing selection, and disruptive selection.
What is directional selection?
Natural selection that favours individuals that differ from the mean phenotype in one direction. Variance stays the same but the mean will shift.
What is beak depth in the medium ground finch population during a drought an example of?
Directional selection.
What is disruptive selection?
Natural selection that favours individuals at the extremes of the phenotypic range to maintain variation.
What is the beak size in black-bellied seed-crackers an example of?
Disruptive selection.
What is stabilizing selection?
Natural selection that favours intermediate or common phenotypes, selecting against extremes. It is common to removes deleterious mutations and maintains genetic fitness.
What is human birth weight an example of?
Stabilizing selection, where extreme birth weights are selected against, promoting average weights for better survival.
What are the modes of evolutionary change?
Mutations, genetic drift, gene flow, non-random mating and natural selection.
What are two large threats to populations?
Extirpation and global extinction.
What processes can affect allele frequencies in populations?
Natural selection, genetic drift and gene flow.
Define genetic drift.
It is a non-adaptive process in which random changes in allele frequencies in a population cause evolutionary change. It can lead to the loss of genetic variation, reducing rare alleles and fix certain alleles. The two main types are the bottleneck effect and founder effect.
What populations does genetic drift effect the most?
Mainly small populations as harmful alleles can become fixed.
Define founder effect.
A type of genetic drift that occurs when a small group of individuals become isolated and establishes a new population, leading to reduced genetic diversity and different allele frequencies compared to the original population.
Define gene flow.
A non-adaptive process that moves alleles throughout populations. It can increase or reduce variation, as the population becomes more homogenous the variation will decrease.
How does gene flow affect the receiving population?
It can increase genetic variation in the receiving population and either increase or decrease the fitness of receiving populations.
How do mutations affect genetic variation in populations?
They occur randomly and create new alleles, either deleterious, neutral or advantageous. Neutral mutations can become harmful or advantageous in the future depending on environmental changes. Chromosomal mutations are often harmful.
What is the importance of whole genome duplication?
It is an important driver for evolution by supplying genetic material and increasing genetic complexity.
Define adaptation.
Traits are selected through natural selection that provides an advantage to an individual possessing it.
Define relative fitness.
The measure of reproductive success.
Define microevolution.
Changes in allele frequencies in populations over generations.
Define the bottleneck effect.
A sudden reduction in population size due to an environmental change that affects allele frequencies. An example of this is the greater prairie chicken population.
What is the biological species concept?
A species is a group of interbreeding individuals that are reproductively isolated from others and exchange genes. It is not applicable to fossils or asexual reproduction and does not account for gene flow between species.
What does prezygotic reproductive barriers prevent?
Fertilization from occurring.
What are the pre-zygotic reproductive barriers?
Habitat isolation, temporal isolation, behavioural isolation, mechanical isolation and gametic isolation.
What are the postzygotic reproductive barriers?
Reduced hybrid viability and fertility or a hybrid breakdown over generations.
What is hybridiztion?
The interbreeding between two related species and can lead to polyploid speciesthat have more than two sets of chromosomes. They often have reduced fertility or survival.
What causes hybridization?
The ability of species with incomplete reproductive barriers to interbreed. Stability continues the formation of hybrids while fusion weakens the reproductive barriers between the species.
Define dispersal.
A type of allopatric speciation occurring when a small population is isolated at the edge of a larger population.
Define vicariance.
A type of allopatric speciation where a range of a species is split by a change in the environment to form two subpopulations.
What is allopatric speciation?
Speciation that occurs when a population is geographically isolated allowing them to evolve independently.
What is sympatric speciation?
Speciation that occurs without geographic separation, often due to reproductive barriers. It can occur when gene flow is reduced by polyploidy and hybridization, habitat differentiation and sexual selection.
