Evolution Flashcards
(74 cards)
1
Q
What is evolution?
A
- the way species adapt to their surroundings
- the scientific theory that describes changes in species over time
- interactions with biotic and abiotic environmental factors
2
Q
What causes evolution?
A
- environmental challenges (severe weather, famine, competition)
- organisms that survive and reproduce can pass their traits to their offspring
3
Q
Adaptation
A
A structural, behavioural, or physiological process that helps an organism to survive and reproduce in a particular environment
4
Q
Structural Adaptation
A
The physical features of an organism (camouflage)
5
Q
Behavioural Adaptation
A
The actions of an organism (migration)
6
Q
Physiological Adaptation
A
The bodily functions of an organism (hibernation)
7
Q
Variations
A
- the differences between individuals of a population
- helpful variations cause the individual to survive longer, produce more offspring, and the characteristic becomes more common
8
Q
Peppered Moths
A
- before Industrial Revolution, the majority of the population was light coloured
- helped them blend into the light forests
- after the IR, the forests turned dark so dark coloured moths had an increased chance of survival
- through natural selection, this trait became more prominent
9
Q
Aristotle Era
A
Believed the earth and all living things could not change
10
Q
Buffon
A
Believed that species had been created in a perfect form, but had changed over time
11
Q
Erasmus Darwin
A
Believed that all life had evolved from a single original source
12
Q
Larmarck
A
- use and disuse, body parts that were not used would disappear and body parts that were used would become larger and stronger
- inheritance of acquired characteristics, individuals pass on characteristics to their offspring that they gained in their lifetime
13
Q
Cuvier
A
Discovered fossils and inferred that life had evolved from simple to complex organisms (catastrophism)
14
Q
Lyell
A
Believed geological change is slow and gradual (uniformitarianism)
15
Q
Malthus
A
Proposed that there was competition between species
16
Q
Darwin
A
- developed the theory of natural selection
- change is slow and gradual
- organisms compete for resources
- variations are heritable
- some characteristics are more advantageous than others
17
Q
Epigenetics
A
The study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself
18
Q
Epigenome
A
A multitude of chemical compounds that tell a genome what to do and modify genes by turning them on or off
19
Q
Fossils
A
- preserved remain or trace of a once living organism
- fossils that are younger and more complex are found closer to the Earth’s surface
- fossils that are older and simpler are found deeper in the ground
20
Q
Biogeography
A
- the study of past and present geographical distribution of organisms
- geographically close environments are populated by similar species
- animals on islands have evolved from marine migrants
21
Q
Homologous Structure
A
structure=same
function=different
-evolved from a common ancestor
22
Q
Analogous Structure
A
structure=different
function=same
-no common ancestor
23
Q
Vestigial Structure
A
- a structure that no longer serves a purpose
- it used to serve a purpose before the evolution of the organism
- body hair and wisdom teeth in humans
24
Q
Embryology
A
- embryos of different organisms can show similar stages during embryonic development
- these similar features indicate a common ancestor
25
DNA
- carries genetic information
- you can compare DNA to determine the relationship between organisms
- the more similar the DNA patterns, the more closely related the organisms are
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Individual
One organism within a population
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Population
A group of individuals within a species
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Species
All members of a population that can interbreed under natural conditions
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Alleles/Traits
One or two alternative forms of a gene that arise by mutation and are found at the same place on a chromosome
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Gene Pool
The sum of all genes in a population
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Gene frequency
The ratio of a particular allele to all other alleles of the same gene in a given population
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Microevolution
Evolution within a single population on a small scale, changes gene frequency within the population
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Macroevolution
Evolution on a large scale, looking at the trends in the diversity of life
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Mutations
- random changes that occur in the DNA of an individual
- creates new genes causing a continual supply of new genetic information
- helps with the genetic variation which increases the diversity of a population and increases a species chance of survival in a changing environment
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Neutral Mutation
Those that provide no benefit or harm to the individual
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Beneficial Mutation
Produce a change in an individual's phenotype that gives the individual an advantage (rare but accumulate)
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Harmful Mutation
Reduce the reproductive success of an individual (common but disappear quickly)
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Pseudogenes
Genes that have undergone mutation and no longer serve a useful purpose
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Gene Flow
The transfer of alleles or genes between populations due to the migration of individuals
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Genetic Drift
The effect on the genetic makeup of a population due to random processes
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Natural Selection
A theory of evolution that states that organisms better adapted to their environment tend to survive longer and produce more offspring which causes these more desirable characteristics to become prominent in the population
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Directional Selection
The environment favours individuals with a more extreme trait
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Stabilizing Selection
The environment favours the most common variation
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Disruptive Selection
The environment favours variations at opposite extremes
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Sexual Selection
The favouring of any trait that specifically enhances the mating success of an individual
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Artificial Selection
The breeding of specific organisms to produce desirable traits.
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Selective Pressures
- disease
- climatic conditions
- food availability
- predators
- selection of mate
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Genetic Drift (detailed)
- the random shifting of the genetic makeup of the next generation
- makeup of the population can change by chance
- the smaller the number of individuals within a population, the larger the effect of genetic drift
- in smaller populations alleles can become popular or disappear quickly
49
Bottleneck
- loss in genetic diversity following an extreme reduction in a population size
- each individual will not contain all of the alleles for the whole population
- rarer alleles are likely to be eliminated
- if the population recovers, the alleles are still limited to those carried by the surviving population and new mutations
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Example of Bottleneck
Cheetahs have low genetic variability and are susceptible to disease because they have no variability in their traits
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Founder Effect
- when a small number of individuals establish a new population
- the founding population has a different gene pool than the initial population
- no increase in diversity of the population
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The Hardy-Weinberg Principle
In large populations, in which only random change is at work, allele frequency is expected to remain constant from generation to generation
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How does evolution happen?
- natural selection
- small population size
- mutation
- immigration and emmigration
- horizontal gene transfer
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Horizontal Gene Transfer
The gaining of new alleles from a different species
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Speciation
Evolutionary process by which populations evolve to become distinct species
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Prezygotic Mechanisms
Prevent fertilization and zygote formation
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Behavioural Isolation
Different species use different courtship and other mating clues to find and attract a mate
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Ecological Isolation
Similar species may occupy different habitats within a region
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Temporal Isolation
Different species breed at different times of the year
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Mechanical Isolation
Differences in morphological features can make two species incompatible
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Gametic Isolation
Male gametes may not be able to recognize and fertilize an egg of a different species
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Postzygotic Mechanisms
Prevents fertilized egg from growing into a viable and reproducing adult
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Zygotic Mortality
Mating and fertilization are possible, but genetic differences result in a zygote that is unable to develop properly
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Hybrid Inviability
A hybrid individual develops but either dies before birth or cannot survive to maturity
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Hybrid Infertility
Hybrid offspring remain healthy and viable but are sterile
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Allopatric Speciation
- single species is separated into two geographically isolated populations
- no longer able to exchange genetic information
- populations become less alike
- mutations that arise are not shared among populations
- reproductive isolating mechanisms arise
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Example of Allopatric Speciation
The Isthmus of Panama separated the Caribbean Sea from the Pacific Ocean
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Sympatric Speciation
When individuals within a population become genetically isolated from the larger population either gradually or suddenly
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Example of Sympatric Speciation
The Hawthorn Fly now has two species, one that lays eggs on hawthorns and one that lays eggs on apples
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Adaptive Radiation
- when a single species evolves into a number of distinct but closely related species
- each species fills a different ecological niche
- occurs when new resources arise that aren't being used by another species
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Divergent Evolution
- species that were once similar diverge and become increasingly distinct
- different traits result from different selective pressures
- increases biodiversity
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Convergent Evolution
- similar traits arise from different species due to adaptation to similar environments
- similar traits result from different selective pressures
- decreases biodiversity
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Co-Evolution
- evolutionary success is closely linked to that of another species
- one environmental change can affect the trait that persists becoming beneficial to both species
- "evolutionary arms race", when two organisms evolve but counter adapt towards new features
- the two species depend on each other
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Examples of Co-Evolution
The gene mutation for lactose and the cultural adaptation of milk have co-evolved
