Biology: Unit 1-Evolution

what is allopatric speciation?

"other country" -gene flow is interrupted or reduced when a population is divided into - The process: separated populations may evolve independently through mutation, natural selection, and genetic drift - The definition of barrier depends on the ability of a population to disperse - For example, a canyon may create a barrier for small rodents, but not birds, coyotes, or pollen

What is sympatric speciation?

"same country" speciation - Occurs in populations that live in the same geographic area - Can occur if gene flow is reduced by three factors including: Polyploidy, Sexual selection, and Habitat differentiation - Ex. the apple maggot lays eggs in an apple, apple falls and decomposes into the ground, maggots dig into the ground

Georges Cuvier

(1769-1832) Largely developed paleontology, the study of fossils.

what is a ring species?

- A situation in which two populations which do not interbreed are living in the same region and connected by a geographic ring of populations that can interbreed

what is the phylogenetic species concept?

- A species is a "tip" on a phylogeny, that is, the smallest set of organisms that share an ancestor and can be distinguished from other such sets

Limitations of the Biological Species Concept

- Cannot be applied to fossils or asexual organisms (including all prokaryotes) - Emphasizes absence of gene flow; however, gene flow can occur between morphologically and ecologically distant species

what is the Ecological species concept?

- Concept of species in which a species is a set of organisms adapted to a particular set of resources, called a niche, in the environment - Implies reproductive isolation of populations inhabiting separate niches as a result of divergent selection of ecologically influenced characters - ex. Grizzly bears mate on land, and the polar bear mate in water. Because they have different habitats, they are also considered different ecological species

what is the Morphological Species Concept?

- Defines species as groups of individuals that are morphologically/anatomically similar to one another and are morphologically/anatomical distinct from other such groups - Organisms are classified in the same species if they appear identical by anatomical criteria - ex. A mule is the offspring of a male donkey and a female horse, both of which belong to different species. Because of differences in the chromosomal makeup of a mule, most are infertile.

Order of the geological record

- Eon-era-period-epoch eon is divided into 4 eras 1. phanerozoic 2. proterozoic 3. archaean 4. hadean

How long does it take for a new species to form?

- Many questions remain concerning how long it takes for new species to form and how many genes need to differ between species

What is the Founder effect?

- Occurs when a few individuals become isolated from a larger population - Ex. Wolves are separated from their pack and then establish a new population in a different area

What is the Bottleneck Effect?

- Occurs when there is a drastic reduction in population size due to a sudden change in the environment - Ex. Hunting of northern elephant seals have reduced genetic variation. Their population has decreased

Why can't natural selection fashion perfect organisms?

- Selection can only act on existing variations - Evolution is limited by historical constraints - Adaptations are often compromises - Chance, natural selection, and the environment interact

How does speciation lead to biodiversity ?

- Since speciation creates new species, it increases biodiversity. Certain environments can drive speciation better than others. - It produces diversity of life on earth by splitting evolutionary lineages through the evolution of reproductive isolation between populations of a species - Ecosystems that have many niches or roles or organisms, have a greater chance at speciation happening. This is because many different variants of a species can each be selected for

Hypothesis

- a specific testable statement about the relationship between two or more variables or proposed explanation for some observable phenomenon - a testable prediction, often implied by a theory

How is evolution both a process and a pattern?

-Evolution is a pattern because it is revealed by a rand of scientific disciplines where natural selection is the pattern. -Evolution is a process because it has mechanisms that produce the observed pattern of change. decent with modification is part of the process.

explain the Theory of Descent with Modification by natural selection

-Individuals with certain heritable traits survive and reproduce at a higher rate than other individuals -Natural selection increases the frequency of adaptation that are favorable in a given environment and if an environment changes over time, natural selection may result in adaptation to these new conditions and give rise to new species -Individuals DO NOT evolve, only populations

Differences/similarities of gene flow and genetic drift

-do not consistently increase the frequency of ales that enhance survival or reproduction -both may increase or decrease frequency of beneficial alleles in population

Theory

-is general enough to spin off of many new, specific hypothesis that can be tested (can explain multiple observations, not specific like a hypothesis, generally supported by a much greater body of evidence) -well-tested explanation that unifies a broad range of observations

How does adaptation relate to natural selection?

Adaptation relates to natural selection because as an individual is able to adapt to its environment, its population is going through natural selection. The population now has individuals with favorable traits, and they will be more likely to survive and reproduce.

What is the Hardy Weinberg Principle?

Allele frequencies in a population remain constant unless one or more factors cause the frequencies to change. -describes the genetic makeup we expect for a population that is NOT evolving at a particular locus

prezygotic barriers

Barriers that impede mating or hinder fertilization (to produce a zygote)

What is a Gene Pool?

Consists of all the alleles for all loci in a population - A locus is fixed if all individuals in a population are homozygous for the same allele. If there are two or more alleles for a locus, diploid individuals may be either homozygous or heterozygous

what is behavioral isolation and example

Courtship rituals and other behaviors unique to a species are effective barriers to mating - Ex. lighting bugs have a different light pattern and will only mate with another lighting bug with the same pattern - Ex. birds that have certain songs or dances will only mate with birds that have the same song or dance

what is the Biological Species Concept?

Defines a species as members of populations that actually or potentially interbreed in nature, not according to similarity or appearance - For example, Western meadowlarks (Sturnella neglecta) and Eastern meadowlarks (Sturnella magna) look almost identical to one another, yet do not interbreed with each other — thus, they are separate species according to this definition.

What are real-world and observable evidence for evolutionary change?

Direct Observations homology the fossil record biogeography sexual selection, intersexual selection, intersexual selection

What is the Hardy-Weinburg Equation

Equation: p2+2pq+q2 = 1 - P2 = expected frequency genotype for homozygous dominant allele in the population - 2pq = frequency of the heterozygous individuals - q2 = expected frequency genotype for homozygous recessive allele in the population

Why is genetic variation important to evolution?

Genetic variation among individuals is caused by differences in genes or other DNA segments -It makes evolution possible -It can introduce traits in an organism that is advantageous and helps the individual survive and reproduce -Variation in heritable traits is a prerequisite for evolution by natural selection -Natural selection can only act on variation with a genetic component -Only genetically determined variation can have evolutionary consequences

how is the fossil record biased

It is biased in favor of species that... -Have existed for a long time -Were abundant and widespread -Had hard parts, such as shells or skeletons Certain conditions have to be met in order for fossils to be formed

What is artificial selection and an example

It is human modification. Humans have modified other species by selecting and breeding. An example of that is dog breeds. We have modified certain breeds so that the dog has favorable traits. We have also done it to certain foods such as corn, cabbage, and brussel sprouts. Natural selection is done by nature and humans do not have a part in natural selection.

What does it mean when a population is in Hardy-Weinberg equilibrium?

It means that the genotype frequencies in a population remain constant between generations in the absence of disturbance by outside factors

what is mechanical isolation and example

Morphological differences can prevent successful completion of mating - Ex. Certain breeds of dogs are morphologically incapable of breeding due to size - ex. snails genitals don't fit in another species of snail

What geological time period are we currently living in ?

Phanerozoic eon, Cenozoic era, Quartenary period, Holocene epoch

How are populations likely to evolve as a result of natural selection and other processes?

Populations can evolve through processes/modification types such as natural selection, artificial selection, genetic drift, and sexual selection.

Charles Darwin

Populations can evolve through processes/modification types such as natural selection, artificial selection, genetic drift, and sexual selection. -He went on a trip which is known as The Voyage of the Beagle He collected specimens of South American plants and animals. -He perceived adaptation to the environment and the origin of new species as closely related processes. -He focused on adaptation and said that natural selection is a process in which individuals with favorable inherited traits are more likely to survive and reproduce -His observations were that individuals in a population vary in their heritable characteristics and that organisms produce more offspring than the environment they can support -His inferences were that individuals that are well suited to their environment ten to leave more offspring and over time, favorable

What is the Fossil record concerning evolutionary change

Provides evidence of the extinction of species, the origin of new groups, and changes within groups over time

Why do only certain species become fossilized?

Some are eaten or decomposed before they can be deposited into layers of sedimentary rocks. The faster that an organism is buried, there is less decay and the better the chance for it to be preserved - what it is buried in too is important because more acidic soil will eat away at the bone and make it fragile

What is temporal isolation and example

Species that breed at different times of the day, different seasons, or different years cannot mix their gametes - Ex. Frogs live in same pond but breed during different seasons (summer vs. spring) - Ex. Flowers release pollen at different times depending on seasons/temperature

What is Biogeography concerning evolutionary change?

The scientific study of the geographic distribution of species, provides evidence of evolution

What is habitat isolation and example

Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not always isolated by physical barriers - Ex. A tiger and lion can potentially interbreed, but usually occupt different habitats - ex northern spotted owl and the Mexican spotted owl live in different locations

Punctual model of speciation

address the rate of speciation; cites fossil evidence that morphological changes required for reproductive isolation evolve in a relatively brief time span

intrasexual selection

an example of nonrandom mating - Direct competition among individuals of one sex (often males for mates of the opposite sex -Ex. Deer fighting, kangaroos fighting

Sexual Selection

an example of nonrandom mating - It is a process in which individuals with certain inherited characteristics are more likely to acquire mates than other individuals of the same sex - Can result in sexual dimorphism, marked differences between the sexes in secondary sexual characteristics

Intersexual selection

an example of nonrandom mating - Often called mate choice, occurs when individuals of one sex (usually females are choosy in selecting their mates - Ex. Mating dances, mating calls, bright feathers

Homologous structures

anatomical resemblances that represent variations on a structural theme present in a common ancestor -Cats, whales, bats, and humans all have the same structure for arms/hands, but they have different functions/roles.

Method of sympatric speciation: HABITAT DIFFERENTIATION

appearance of new ecological niches -populations of North American maggot fly can live on native hawthorn trees, as well as more recently introduced apple trees

Evolutionary Trees

are diagrams that reflect hypotheses about the relationships among different groups -homologies form nested patterns in evolutionary trees -can be made using different types of data, for example, anatomical and DNA sequence

Vestigial Structures

are remnants of features that serve as a function in the organisms' ancestors -Wisdom teeth, tail bone

How can natural selection alter allele frequencies in a population?

because of natural selection, organisms mate with one another which shift allele frequencies depending on who they mate with

Regional Adaptive Radiation

can occur when organisms colonize new environments with little competition -ex. the Hawaiian islands are one of the world's greatest showcases. the "silversword alliance" is a diverse group of plants descended from an ancestral tarred that arrived about 5 million years ago

mass extinction and consequences

caused by changes to a specific biotic or abiotic environment -the rate of extinction has increased dramatically which causes mass extinction consequences: -can change the types of organisms found in ecological communities - ex. the proportion of predators increased in marine communities after the Permian and Cretaceous mass extinctions it typically takes 5-10 million years for diversity to recover following a mass extinction; in some cases, up to 100 million years

What is microevolution?

change in allele frequencies in a population over generations -there are three main mechanisms that cause allele frequencies to change 1.natural selection 2.genetic drift 3.gene flow

Gene flow

consists of the movement of alleles among populations - Alleles can be transferred through the movement of fertile individuals or gametes (for example, pollen)

genetic drift

describes how allele frequencies fluctuate unpredictably from one generation to the next - tends to reduce genetic variation through the random loss of alleles - The smaller the sample, the greater the chance of random deviation from a predicted result - Significant in small populations - Kind of based on LUCK/CHANCE - Can cause harmful alleles to become fixed

what are the three modes of natural selection

directional selection, disruptive selection, stabilizing selection

disruptive selection

favors individuals at both extremes of the phenotypic range

directional selection

favors individuals at one extreme end of the phenotypic range

stabilizing selection

favors intermediate variants and acts against extreme phenotypes

what are some Barries to reproductive isolation?

habitat isolation temporal isolation behavioral isolation mechanical isolation gametic isolation

Example of Homology concerning evolutionary change

homology is similarity resulting from common ancestry -there are three types of structures concerning homology 1. homologous structures: are anatomical resemblances that represent variations on a structural theme present in a common ancestor (Cats, whales, bats, and humans all have the same structure for arms/hands, but they have different functions/roles.) 2. Vestigial structures: are remnants of features that serve as a function in the organisms' ancestors (Wisdom teeth, tail bone) 3. Comparative embryology: embryology reveals anatomical homologies not visible in adult organisms (All vertebrate embryos have a post-anal tail and pharyngeal arches)

Jean Baptiste de Larmark

hypothesizes that species evolve through the use and disuse of body parts (the idea that parts of the body that are used extensively become larger and stronger, while those that are not used deteriorate) and evolution is the inheritance of acquired characteristics -He was wrong in saying this because it was supposed to be inheritable

How could a population break the assumption of "large population" regarding a population in HWE

if there is a small population: -in a small population, allele frequencies fluctuate by chance over time (a process called genetic drift)

How could a population break the assumption of "no migration/gene flow" regarding a population in HWE

if there is migration/gene flow: by moving alleles into or out of populations, gene flow can alter allele frequencies

How could a population break the assumption of "no mutation" regarding a population in HWE

if there is mutation: the gene pool is modified if mutations occur or if entire genes are deleted or duplication

How could a population break the assumption of "no natural selection" regarding a population in HWE

if there is natural selection: allele frequencies change when individuals with different genotypes show consistent differences in their survival or reproductive success

How could a population break the assumption of "random mating" regarding a population in HWE

if there is not random mating: if individuals' mate within a subject of the population, such as near neighbors or close relatives (inbreeding), random mixing of gametes does not occur and genotype frequencies change

Method of sympatric speciation: SEXUAL SELECTION

is a process in which individuals with certain inherited characteristics are more likely to acquire mates than other individuals of the same sex -different colors has likely contributed to speciation in cichlid fish in Lake Victoria

Method of sympatric speciation: POLYPLOIDY

is the presence of extra sets of chromosomes due to accidents during cell division -much more common in plants than animals -can produce new biological species in sympatry within a single generation -many important crops such as oats, cotton, potatoes, tobacco, and wheat are polyploids -plant geneticists can produce new polyploid agricultural species using chemicals to induce errors in cell divisions -ex. Genus Tragopogon, two polyploid species have evolved from three diploid parent species

why are fossils important when studying evolution?

it documents the history of life

What is convergent evolution?

it is the evolution of similar or analogous features in distinctly related groups -homologous structures: anatomical resemblances that represent variations on a structural theme present in a common ancestor (Ex. Cats, whales, bats, and humans all have the same structure but different functions) -analogous structures: traits that arise when groups independently adapt to similar environments in similar ways

Worldwide Adaptive radiation

mammals underwent an adaptive radiation after the extinction of terrestrial dinosaurs -ex. the disappearance of dinosaurs opened ecological niches, allowing for the expansion of mammals in diversity and size

why are there seperations in the geological record?

mass extinctions

compare microevolution from macroevolution

microevolution: change in allele frequencies in a population over generations macroevolution: broad patters of evolutionary change above the species level

What are some sources of genetic variation in populations?

mutations, gene duplication, sexual reproduction, recombination/reshuffling, and immigrations of genes/gene flow

5 assumptions regarding a population in Hardy-Weinberg Equilibrium

no selection, no mutation, no migration/gene flow, large population, random mating

How can gene flow alter allele frequencies in a population?

one population moves to another population causing a change in allele frequencies

postzygotic barriers

reduced hybrid viability, reduced hybrid fertility, hybrid breakdown - reduced hybrid viability: genes of the different parent species may interact and impair the hybrid's development or survival in its environment - reduced hybrid fertility: even if hybrids are vigorous, they may be sterile - hybrid breakdown: some first-generation hybrids are fertile, but when they mate with each other or with either parent species, offspring of the next generation are feeble or sterile

Explain how the biological species concept emphasizes reproductive isolation.

reproductive isolation: is the existence of biological factors (barriers) that impede two species from producing viable, fertile offspring

Natural selection

results in alleles being passes to the next generation in proportions that differs from those in the present generation -can cause adaptive evolution -involves both chance and "sorting" -consistently increases the frequencies of ales that provide reproductive advantage -favors certain genotypes by acting on phenotypes of individuals -ex. the jaws of snakes allow them to swallow prey larger than their heads

Comparative embryology

reveals anatomical homologies not visible in adult organisms -All vertebrate embryos have a post-anal tail and pharyngeal arches

gradual model of speciation

species diverge at a slow, steady pace as traits change incrementally

what is gametic isolation and example

sperm of one species may not be able to fertilize eggs of another species - Ex. Sea urchins cannot fertilize with another species of sea urchins

Example of Direct Observations concerning evolutionary change?

the evolution of drug resistant bacteria -The bacteria staphylococcus aureus is commonly found in people. One strain, methicillin-resistant staphylococcus aureus (MRSA) is a dangerous pathogen. Resistance to penicillin evolved in staphylococcus by 1945, two years after it was first used.

What is speciation?

the process by which one species split into two or more species, is at the focal point of evolutionary theory

What is adaptive radiation ?

the rapid evolution of diversely adapted species from a common ancestor they typically follow after... -mass extinctions -evolution of novel characteristics -colonization of new regions

How can genetic drift alter allele frequencies in a population?

there is a randomness to genetic drift causing allele frequencies to shift