Biology 2130 Exam 1

typological thinking

based on the idea that species are unchanging types and that variations within species are unimportant or even misleading

population thinking

variation among individuals in a population was the key to understanding the nature of species

paradigm shift

a major change in basic assumptions of a particular scientific discipline

vestigial traits

Traits that were useful in ancestors that are inherited today, but that have lost their original use.

structural homology

The study of similar structures in different species

Plato

Typological Thinking(species never change and are created by god)

Aristole

Humans are better species than any other

Lamarck

Lower species grow to become better species through evolution to become humans

Darwin

natural selection(population thinking)

geologic time

Earth's history as revealed by layers of rock

Extinction

A term that typically describes a species that no longer has any known living individuals.

transitional feature

a trait in a fossil species that is intermediate between those of ancestral and derived species

Darwin's 4 postulates

1. Individuals in a population vary in their traits

2. Some of these differences are heritable; they are passed on to offspring

3. In each generation, many more offspring are produced than can survive

4. Individuals with certain heritable traits are more likely to survive and reproduce

populations

Do individuals or populations evolve?

altruism

unselfish regard for the welfare of others

natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

genetic drift

A change in the allele frequency of a population as a result of chance events rather than natural selection.

gene flow

movement of alleles from one population to another

Mutation

a random error in gene replication that leads to a change

Hardy-Weinberg equilibrium

condition that occurs when the frequency of alleles in a particular gene pool remain constant over time
1)Random Mating
2)no natural selection
3)no genetic drift
4)no gene flow
5)no mutations

gene pool

Combined genetic information of all the members of a particular population

Inbreeding

Continued breeding of individuals with similar characteristics

Effects of inbreeding

-increases the frequency of homozygotes
-reduces the frequency of heterozygotes
-decline in fitness
-doesn't cause evolution

deleterious

causing harm or damage

Effects of inbreeding depression

increases homozygosity and lowers heterozygosity

ecological selection

Also known as environmental selection. A type of natural selection that favors individuals with heritable traits that enhance their ability to survive and reproduce in a certain physical and/or biological environment, excluding their ability to obtain a mate.

genetic variation

Heritable variations in a population.

directional selection

Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve

stabilizing selection

Natural selection that favors intermediate variants by acting against extreme phenotypes

disruptive selection

favors individuals at both extremes of the phenotypic range

balancing selection

occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population

purifying selection

selection against deleterious changes

Causes of heterozygosity advantage

Balancing selection and maintaining genetic variation

frequency-dependent selection

the fitness of a phenotype depends on how common it is in the population

intersexual selection

M+F

intrasexual selection

M+M or F+F

founder effect

change in allele frequencies as a result of the migration of a small subgroup of a population

genetic bottleneck

a sudden reduction in the number of alleles in a population

point mutation

gene mutation in which a single base pair in DNA has been changed

Beneficial Mutation

any change to the genetic code that results in noticeable physiological changes that are of benefit to the organism

deleterious mutation

Genetic changes that are harmful to an organism.

silent mutation

alters a base but does not change the amino acid

Genetic Drift-

-Decreases genetic Variation

Natural selection-

-May increase, decrease, or maintain genetic variation

Gene Flow-

-may increase or decrease genetic variation

Mutation-

-increases genetic variation

prezygotic isolation

a barrier to successful breeding that occurs before fertilization, such as differences in mating time or behavior

temporal isolation

form of reproductive isolation in which two populations reproduce at different times

habitat isolation

When two species encounter each other only rarely.

behavioral isolation

Form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding

gametic barrier

prezygotic barrier occurring when closely related individuals of different species mate, but differences in their gamete cells (eggs and sperm) prevent fertilization from taking place

mechanical isolation

Morphological differences prevent fertilization.

postzygotic barriers

Barriers that prevent the hybrid zygote from becoming a fertile adult.

hybrid viability

offspring die as embryos

hybrid sterility

hybrids fail to produce functional gametes

morphospecies species concept

defined by morphological characteristics; individuals that share many morphological features are considered one species

polymorphic species

species with differing phenotypes

cryptic species

Groups of organisms that are genetically distinct and do not interbreed, but are morphologically almost indistinguishable ex. Dolphin and Ichthyosaurus(Are very similar but are very different in traits)

phylogenetic species concept

A definition of species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life.

Allopatry

populations that live in different areas

Sympatry

species living in the same geographic area

sympatric speciation

The formation of new species in populations that live in the same geographic area

Niche

Full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions

Polyploidy

A chromosomal alteration in which the organism possesses more than two complete chromosome sets. (ex. Plants and INTERNAL SYMPATRIC SPECIATION)

allopatric speciation

The formation of new species in populations that are geographically isolated from one another.

outgroup

generally, any group that one does not belong to

synamorphy

shared derived trait

Clade

A group of species that includes an ancestral species and all its descendants.

parsimony

Filter that suggests that the tree requiring the fewest character changes is most likely

Evolutionary distance

A measure of how far apart two organisms are on the evolutionary scale.

Bayesian analysis

additional information is used to alter the marginal probability of the occurrence of an event

convergent evolution

Process by which unrelated organisms independently evolve similarities when adapting to similar environments

intact fossil

forms when decomposition does not occur and the organic remains are preserved intact

compression fossil

Carbon prints formed when the crushing weight of overlying sediments squashed the organism flat.

Sister Groups

2 lineages that are the closest relatives, represented by 2 branches emerging from a node

cast fossil

forms when a mold is filled with sand or mud that hardens into the shape of the organism

permineralized fossil

forms when organisms decompose extremely slowly. dissolved minerals gradually infiltrate the interior of cells and harden into stone

trace fossil

A type of fossil that provides evidence of the activities of ancient organisms

Precambrian

Name for the time in earths early history that accounts for ninety percent of earth's time, but only cellular organisms lived.

Phanerozoic

visible life

Paleozoic Era

the part of geologic time 570-245 million years ago ; invertebrates, fishes, amphibians, reptiles, ferns, and cone-bearing trees were dominant

Mesozoic Era

Age of reptiles

Cenozoic Era

Age of mammals

Hox genes

Class of homeotic genes. Changes in these genes can have a profound impact on morphology.

adaptive radiation

An evolutionary pattern in which many species evolve from a single ancestral species

Ecomorph

species with the same structural habitat/niche, similar in morphology and behavior, but not necessarily close phyletically

Cambrain explosion

earliest part of the Paleozoic era, when a huge diversity of animal species evolved

Triggers of Cambrian Explosion

-higher oxygen levels
-evolution of predation
-new niches beget more new niches
-new genes, new bodies

mass extinction

event in which many types of living things become extinct at the same time

impact hypothesis

The hypothesis that a collision between the Earth and an asteroid caused the mass extinction at the K-P boundary, 65 million years ago.