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Biosphere at Risk > Chapter 3 > Flashcards

Chapter 3 Flashcards

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1
Q

Evolution

A

change in populations of organisms from generation to generation

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2
Q

Natural Selection

A

inherited characteristics that enhance survival and reproduction are passed on more frequently to future generations; alters genetic makeup of populations over time

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3
Q

Logic of natural selection: Premises

A
  • organisms struggle to survive; competition for resources
  • more offspring produced than can survive; overproduction of offspring
  • individuals vary in characteristics
  • many characteristics are inherited
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4
Q

Logic of natural selection: Conclusions

A
  • some individuals are better suited to environment
  • individuals better suited are more fit
  • future generations have more characteristics from fit individuals
  • characteristics evolve over time
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5
Q

Fitness

A

increased survivorship and ability to reproduce

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6
Q

Sources of sexual reproduction

A
  • independent assortment
  • crossing over
  • random fertilization
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7
Q

Species

A

a particular type of organism; a population of a particular type of organism that shares certain characteristics and can breed with one another

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8
Q

Population

A

a group of individuals of a given species that live in a particular region at a particular time

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9
Q

Allele

A

form of a gene; one of two or more versions of a gene; inherits two alleles for each gene, one from each parent

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10
Q

Genetic Mutations

A

accidental changes in DNA; where genetic variation comes from

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11
Q

Adaptation

A

from one generation to another through time, characteristics or traits that lead to better and better reproductive success will evolve in a population; dependent on the environment

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12
Q

Adaptive traits

A

trait that promotes success; i.e. colorful bird attracts mate so more offspring, colorful plant attracts pollinators; camoflauge, warning coloration

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13
Q

Genetic variation

A

diversity in gene frequencies; created by genetic mutations and sexual reproduction; changes in nucleotides; natural selection acts on genetic variation

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14
Q

Sexual reproduction

A

each parent contributes genes to the offspring, producing different combinations of genes and generating variations among individuals

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15
Q

Directional selection

A

a mode of natural selection in which a single phenotype is favored causing the allele frequency to shift in one direction

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16
Q

Stabilizing selection

A

favors the average individuals in a population; genetic diversity decreases as the population stabilizes on a particular trait value

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17
Q

Disruptive selection

A

selects against the average individual (i.e. diversifying); extreme values for a trait are favored over intermediate ones; can drive toward speciation

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18
Q

Convergent Evolution

A

very unrelated species acquire similar traits as they adapt to selective pressures from similar environments; i.e similar form of cactus in desert vs. euphorb they look the same but produce different flower

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19
Q

Divergent Evolution

A

closely related species that live in different environments; diverge their traits that they adapted to different food resources and habitats; selective pressures; breeding and resources use being separated can drive this; allopatric speciation is an example of divergent evolution

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20
Q

Genetic Drift

A

random fluctuations in the number of gene variants; variation in the relative frequency of different genotypes in a small population; from individuals dying or not reproducing; i.e. bottleneck and founder effect

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21
Q

Gene Flow

A

AKA migration; transfer of alleles or genes from one population to another; gametes spread through pollen or in ocean in water currents

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22
Q

Artificial selection

A

natural selection conducted by human direction; i.e. selective breeding of crops, pets and livestock

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23
Q

Speciation

A

process where new species are generated (microevolution)

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24
Q

Allopatric speciation

A

species form populations that become physically separated over some geographic distance; i.e. mountain, natural disaster, etc

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25
Sympatric speciation
new species evolve from a single ancestral species while inhabiting the same geographic region
26
Charles Darwin
discovered that natural selection explained the world's variety of living things; studied finches on the Galapagos Islands; book on the Origin of Species
27
Alfred Russel Wallace
shared the same ides as Darwin; Both British naturalists; also published a paper
28
Fossil record
cumulative body of fossils worldwide, which paleontologists study to infer the history of past life on Earth
29
Phylogenetic trees
a tree-like diagram that represents the evolutionary history of divergence of species or taxonomic groups of organisms
30
Taxonomy
study of classification of organisms; creates heirarchy
31
Conclusions from fossil records
- life is greater than 3.5 billion years old - earlier species evolved into later ones; continuous evolution since life first appeared - number of species has increased over time - vast majority of species are extinct - there has been several mass extinctions; currently in the middle of one
32
Organism
an individual living thing
33
Population
a group of individuals of a species that live in a particular area
34
Community
a set of populations of different species living together in a particular area
35
Ecosystem
a functional system consisting of a community, its nonliving environment (abiotic) and the interactions between them
36
Landscape
a geographic region including an array of ecosystems
37
Biosphere
the sum total of living things on Earth and the areas they inhabit
38
Habitat
the specific environment an organism lives; i.e. house
39
Niche
an organism's functional role in a community; reflects use of habitat and resources, flow of energy interactions with others, etc; i.e. lifestyle
40
Niche specialist
narrow breadth and very specific requirement of an organism
41
Niche generalist
able to use a wide array of resources; broad tolerances/breadth; "jack of all trades"
42
Population size
the number of individual organisms present at a given time; can change; bigger size more genetic diversity
43
Population Density
the number of individuals per unit area in a population; increases resource competition; more safe in a large herd but bigger target; increases chances of finding a mate
44
Population distribution
the spatial arrangement of organisms in an area
45
Random Distribution
no pattern; happens when abiotic means (wind, water) disperses seeds/larvae
46
Uniform Distribution
individuals spaced evenly; competition for territory and resources (penguins, loons, etc)
47
Clumped Distribution
individuals congregate in certain areas; organisms follow resources; i.e. vegetation near water/ herbivores near plants
48
Sex ratio
proportion of males to females in a population; 1:1 ratio maximizes population growth but does not need to be 1:1; alpha male, pregnancy time, may need more females
49
Age Structure
the relative number of individuals of different ages within a population; can be used to predict if a population will grow or shrink
50
Survivorship curves
graph showing the number or proportion of individuals surviving each age for a given species or group; type 1=few offspring i.e. humans, elephants; type 2=songbirds, housefly; type 3=lots of offspring, frogs, sea turtles, plants
51
Demographers
scientists who study human populations; statistical study of any population
52
Population change is determined by
- Natality: births within the population - Mortality: deaths within the population - Immigration: arrival of individuals from outside population - Emigration: departure of individuals from population
53
Population growth rate
the total rate of change in a population's size per unit time population growth rate=(birth rate-death rate)+(immigration rate-emigration rate)
54
Rate of Natural Increase
birth rate-death rate
55
Exponential Growth Curve
when a population increases by a fixed percentage each year; unrestricted growth; positive feedback loop
56
Intrinsic Growth Rate
the rate at which a population increases in size with no density dependent forces regulating it; steepness of curve
57
Biotic Potential
ability to reproduce quickly and a lot of offspring; dependent on generation time and offspring number, offspring survival;density dependent; restricted by environmental resistance, any condition that inhibits the increase in number of the population; i.e. rabbits have high biotic potential
58
Logistic Growth
population may increase rapidly at first. then slow, and finally stabilize at carrying capacity
59
Carrying Capacity
the maximum population size of a species that an environment can sustain
60
Density-dependent
the condition of a limiting factor whose effects on a population increase or decrease depending on the population density; associated with K; more competition, etc with higher density
61
Density-independent
the condition of a limiting factor whose effects on a population are constant regardless of population density; fire, flood, volcanic eruption; abiotic things will negatively effect everyone
62
r selection
lots of offspring, short generation time, not much parental care, tend to be niche generalists, more competitors, good colonizers
63
k selection
high parental care, few slowly developing large offspring, specialist niche, good competitors
64
Specialist benefits
- really well adapted to specific resources - more efficient use of resources - good at avoiding direct competition
65
Specialist Disadvantages
- smaller habitat use | - more vulnerable to changing conditions that can cause extinction
66
Generalist Benefits
- use larger habitat | - less vulnerable to changing conditions
67
Generalist Disadvantages
- less efficient in use of resources - more competition - not adapted to specific resources

Biosphere at Risk (4 decks)

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