G11 Biology Unit 4 Evolution

neutral mutation

a mutation that does not result in any selective advantage or disadvantage

harmful mutation

any mutation that reduces the reproductive success of an individual and is therefore selected against; harmful mutations do not accumulate over time

beneficial mutation

any mutation that increases the reproductive success of an organism; beneficial mutations are favored by natural selection and accumulate over time

artificial selection

directed breeding in which individuals that exhibit a particular trait are chosen as parents of the next generation; artificial selection is used to produce new breeds or varieties of plants and animals

immutable

unable to change

fossil

any ancient remains, impressions, or traces of an organism or traces of its activity that have been preserved in rocks or other mineral deposits in Earth’s crust

paleontology

the scientific investigation of prehistoric life through the study of fossils

catastrophism

the theory that the pattern of fossils could be accounted for by a series of global catastrophes that wiped out most species on Earth

uniformitarianism

the theory that geological changes are slow and gradual and that natural laws and processes have not changed over time

biogeography

the scientific study of the geographic distribution of organisms based on both living species and fossils

homologous feature

a structure with a common evolutionary origin that may serve different functions in modern species (for example, bat wing and human arm)

analogous feature

a structure that performs the same function as another but is not similar in origin or anatomical structure; for example, bird and insect wings

vestigial feature

a rudimentary and non-functioning, or only marginally functioning, structure that is homologous to a fully functioning structure in closely related species

natural selection

the way in which nature favors the reproductive success of some individuals within a population over others

survival of the fittest

a phrase that has been used to describe the process of natural selection

adaptation

a characteristic or feature of a species that makes it well suited for survival or reproductive success in its environment

directional selection

selection that favors an increase or decrease in the value of a trait from the current population average

stabilizing selection

selection against individuals exhibiting traits that deviate from the current population average

disruptive selection

selection that favors two or more variations of a trait that differ from the current population average

sexual selection

differential reproductive success caused by variation in the ability to obtain mates; results in sexual dimorphism, and mating and courtship behaviors

genetic drift

changes to allele frequency as a result of chance; such changes are much more pronounced in small populations

genetic bottleneck

a dramatic, often temporary, reduction in population size, usually resulting in significant genetic drift

founder effect

genetic drift that results when a small number of individuals separate from their original population and establish a new population

Hardy–Weinberg principle

in large populations in which only random chance is at work, allele frequencies are expected to remain constant from generation to generation

microevolution

changes in gene (allele) frequencies and phenotypic traits within a population and species

Bipedal

Walking on two legs

speciation

the formation of new species

Foramen Magnum

A large opening at the base of the skull through which the spinal cord connects to the brain.

reproductive isolating mechanism

any behavioral, structural, or biochemical trait that prevents individuals of different species from reproducing successfully together

Hominid

Humans, Chimpanzees, and other great apes, such as orangutans and gorillas.

prezygotic mechanism

a reproductive isolating mechanism that prevents interspecies mating and fertilization (for example, ecological isolation, temporal isolation, and behavioral isolation)

Hominin

Humans and human-like ancestors, such as homo habilis and homo erectus.

postzygotic mechanism

a reproductive isolating mechanism that prevents maturation and reproduction in offspring from interspecies reproduction

What happened to the position of the foramen magnum as hominins evolved into modern humans?

The foramen magnum moved forward towards the middle of the skull, in order to accomodate a bipedal posture.

allopatric speciation

the formation of a new species as a result of evolutionary changes following a period of geographic isolation

Cranial capacity

The size of the space occupied by the brain.

sympatric speciation

the evolution of populations within the same geographic area into separate species

This happened to the size of the brain as hominins evolved

Brain size increased

adaptive radiation

the relatively rapid evolution of a single species into many new species, filling a variety of formerly empty ecological niches

What came first: bipedalism or large brains?

Bipedalism came before large brains. Measurements show that the foramen magnum moved forward towards the middle of the skull, in order to accomodate a bipedal posture, well before the increase in cranial capacity.

divergent evolution

the large-scale evolution of a group into many different forms

What is cranial capacity a good indicator of?

Cranial capacity is a good indicator of intelligence.

convergent evolution

the evolution of similar traits in distantly related species

How did the increase in cranial capacity affect the use of tools?

As the size of the brain increased, the use of tools became more common.

coevolution

a process in which one species evolves in response to the evolution of another species

macroevolution

large-scale evolutionary changes including the formation of new species and new taxa

How did the increase in tool use affect the size of the jaws and teeth as hominins evolved?

The use of tools made large protruding jaws with giant teeth unnecessary, so jaws and teeth slowly evolved to be smaller

abiogenesis

the origin of life from non-living matter

Cranium

The portion of the skull that encloses the brain

Cambrian explosion

the rapid evolution of most major animal phyla that took place over approximately 40 million years during the Cambrian period

What is the relationship between the evolution of bipedalism, the increase in cranial capacity, and the decrease in tooth and mouth size in hominins?

The evolution of bipedalism freed the hands for other uses. The increase in cranial capacity implies a larger brain, which would lead to an increase in intelligence. Both are linked to the development of sophisticated stone tools and the use of fire. Wth stone tools to cut up food, and fire to cook it with, large and powerful teeth and jaws became unnecessary.

cladistics

a method of determining evolutionary relationships based on the presence or absence of recently evolved traits

Summarize how hominins changed as they evolved.

As hominins evolved, their posture became more upright over time. Probably the first bipedal hominins' still spent some time living in trees, but progressive hominin species slowly moved out of trees, using walking to get around.As hominin posture became more erect, their brain size increased, leading to an increase in intelligence and tool use. The tool use led to an increase in the amount of processing the food underwent. As food processing increased, the mouth and tooth size decreased, leading to the flattened features that humans now possess.

derived trait

a trait that has evolved relatively recently with respect to the species or groups being discussed

synapomorphy

a derived trait shared by two or more species or groups

theory of punctuated equilibrium

a theory that attributes most evolutionary changes to relatively rapid spurts of change followed by long periods of little or no change

primate

a group of relatively large-brained, mostly arboreal mammals that includes prosimians, monkeys, apes, and humans

prosimian

the group of primates that includes lemurs, lorises, and tarsiers

anthropoid

the group of primates that includes monkeys, apes, and humans

hominid

all species descended from the most recent common ancestor of chimpanzees and humans that are on the human side of the lineage

neutral mutation

a mutation that does not result in any selective advantage or disadvantage

harmful mutation

any mutation that reduces the reproductive success of an individual and is therefore selected against; harmful mutations do not accumulate over time

beneficial mutation

any mutation that increases the reproductive success of an organism; beneficial mutations are favored by natural selection and accumulate over time

artificial selection

directed breeding in which individuals that exhibit a particular trait are chosen as parents of the next generation; artificial selection is used to produce new breeds or varieties of plants and animals

immutable

unable to change

fossil

any ancient remains, impressions, or traces of an organism or traces of its activity that have been preserved in rocks or other mineral deposits in Earth’s crust

paleontology

the scientific investigation of prehistoric life through the study of fossils

catastrophism

the theory that the pattern of fossils could be accounted for by a series of global catastrophes that wiped out most species on Earth

uniformitarianism

the theory that geological changes are slow and gradual and that natural laws and processes have not changed over time

biogeography

the scientific study of the geographic distribution of organisms based on both living species and fossils

homologous feature

a structure with a common evolutionary origin that may serve different functions in modern species (for example, bat wing and human arm)

analogous feature

a structure that performs the same function as another but is not similar in origin or anatomical structure; for example, bird and insect wings

vestigial feature

a rudimentary and non-functioning, or only marginally functioning, structure that is homologous to a fully functioning structure in closely related species

natural selection

the way in which nature favors the reproductive success of some individuals within a population over others

survival of the fittest

a phrase that has been used to describe the process of natural selection

adaptation

a characteristic or feature of a species that makes it well suited for survival or reproductive success in its environment