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Ecology > Evolution and Ecology > Flashcards

Evolution and Ecology Flashcards

1
Q

Genotype

A

The genetic makeup of an individual.

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2
Q

Phenotype

A

Observable characteristics that are determined by the genotype

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3
Q

Evolutionary Mechanisms

A
  • Gene Flow
  • Mutation
  • Genetic Drift
  • Natural Selection
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4
Q

Mutation

A
  • Changes DNA sequence of a gene
    • low rate in nature
  • The ultimate cause of all genetic variation
  • Most neutral or deleterious; rarely beneficial
  • Different alleles arise by mutation—a change in DNA
  • Mutations can result from copying errors during cell division, mechanical damage, exposure to chemicals (mutagens) or high-energy radiation.
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5
Q

Gene Flow

A
  • Introduction of new alleles by the movement of individuals among populations
    • Population= interbreeding group of individuals (of the same species)
  • Alleles move between populations via movement of individuals or gametes.
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6
Q

Gene Flow has two effects:

A
  1. Populations become more similar
  2. New alleles can be introduced into a population

Example: Lynx canadensis

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7
Q

Genetic Drift

A
  • Changes in allele frequencies caused by chance (stochastic) events
  • Effects proportional to population size
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8
Q

Genetic drift has four effects on small populations:

A
  1. It acts by chance alone, thus causing allele frequencies to fluctuate at random.
    * Some may disappear, others may reach 100% frequency (fixation).
  2. Because some alleles are lost, genetic variation of the population is reduced.
  3. Frequency of harmful alleles can increase if the alleles have only mildly deleterious effects.
  4. Differences between populations can increase. Chance events may lead to allele fixation in one population and loss from another population.
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9
Q

Natural Selection

A

The process whereby organisms better adapted to their environment tend to survive and produce more offspring.

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10
Q

Natural Selection pt. 2

A

Adaptive: increases frequency of beneficial alleles relative to the current environment

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11
Q

Evolution:

A

Change in allele frequencies (proportions) in a population over time.

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12
Q

What is evolution?

A
  • Evolution can be defined more broadly as descent with modification.
  • As a population accumulates differences over time and a new species forms, it is different from its ancestors
  • But the new species has many of the same characteristics as its ancestors and resembles them.
  • If two populations experience different environmental conditions, different characteristics may be favored.
  • Natural selection causes the populations to diverge genetically over time.
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13
Q

Peppered moth (Biston betularia) - Polymorphic melanism (“industrial melanism”)

A

The melanistic condition is an inherited trait determined by a single dominant gene.

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14
Q

Peppered moth (Biston betularia)

A
  • Decrease in the melanistic form of peppered moth following pollution control programs in England in the 1960’s. (Decrease in melanics from 90% to 30% by 1990)
  • The lag in evolutionary response, relative to the decrease on SO2 emissions reflects the time for the forest to return to an unpolluted state (less sooty bark), as well as the low frequency of the recessive allele for typical (light) coloration.
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15
Q

What is Evolution pt. 2

A
  • Natural selection acts as a sorting process.
  • Individuals with favored traits have more offspring, and their alleles will increase in frequency in the population
  • The population will evolve, but individuals do not evolve.
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16
Q

Mechanisms of Evolution

A
  • Formation of new alleles is critical to evolution.
  • If mutation did not produce new alleles, all members of a population would have identical genotypes and evolution could not occur
17
Q

Mechanisms of Evolution

A
  • Recombination also produces different genotypes within a population
  • Offspring have combinations of alleles that differ from those of their parents
  • Mutation provides the raw material on which evolution is based; recombination rearranges the raw material into new combinations.
18
Q

Three types of natural selection: Directional selection

A
  • Individuals at one phenotypic extreme (e.g., large size) are favored.
  • Example: In the Galapagos, prolonged drought resulting large, hard seeds favored large beak size in medium ground finches.
19
Q

Three types of natural selection: Stabilizing selection:

A

Individuals with an intermediate phenotype are favored

Example: Eurosta flies parasitize goldenrods:

Parasitic wasps select for small gall size of Eurosta flies; while birds select for large gall size.

20
Q

Three types of natural selection:

A
  • Individuals at both phenotypic extremes are favored.
  • Example: African seedcrackers (birds) have two food sources—hard seeds that require large beaks to crack, and smaller, softer seeds that smaller beaks are more suited to.
21
Q

Concept 6.2

A
22
Q

Mechanisms of Evolution pt. atchu

A
  • Natural selection can result in populations in which all individuals have the favored allele:
  • Andean geese have evolved a type of hemoglobin with a very high affinity for O2 , an advantage at high altitudes.
  • The allele frequency for this trait is 100%.
23
Q

Trophy Hunting

A
  • Trophy hunting removes the largest and strongest males—the ones that would sire many healthy offspring
  • In one population, 10% of males were removed by hunting each year.
  • The average size of males and their horns decreased over 30 years of study.
24
Q

Concept 6.3

A
25
Q

Adaptive Evolution

A
  • Adaptations are features of organisms that improve their ability to survive and reproduce.
  • Adaptations include morphological and physiological features such as enzymes that function at high temperatures.
26
Q

Adaptive Evolution and Natural Selection

A
  • Natural selection is not a random process!!
    • By consistently favoring individuals with certain alleles, natural selection causes adaptive evolution—traits that confer advantages tend to increase in frequency over time.
27
Q

Evolutionary Ecology- Ecological interactions drive natural selection:

A
  • Predation, pathogens cause outright mortality
  • Food resources determine reproductive capacity (e.g., caribou body condition)
  • Challenges in physical environment draw energy away from reproduction
  • Mutually beneficial interactions can extend lifespan, resources, reproduction
  • The outcome of factors such as these affects the fitness (relative contribution of genes to the next generation), the components of which are survival & reproduction
28
Q

Natural Selection Part Atchu 1

A

that interaction between heritable phenotypic variation and the environment that leads to differences in reproductive success among individuals within populations

3 necessary conditions:

  • Genetic basis
  • Variation within population
  • Trait linked to reproductive success

Ecology (5 decks)

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