Ecology and Evolution Exam 1

What is evolution?

The change in the genetic composition of a population from generation to generation.

What did Darwin believe about evolution?

Species in a population are descendants of ancestral species that are morphologically different from present-day species (Descent with Modification)

What is natural selection?

Genetically altered traits enhance survival and reproduction. Individuals of that population that did not inherit those favorable traits are selected against (die off) by their environment

What is the pattern of evolution?

observations about the natural world—and these observations show that life has evolved over time

How did Malthus influence Darwin?

Darwin realized that the capacity to overreproduce was characteristic of all species;
-Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than do other individuals.
-This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations.

What is catastrophism?

The belief that the Earth's past geological changes were caused by sudden, violent changes in the Earth's surface.

Who believed in catastrophism?

Cuvier; speculated that each boundary between strata represented a sudden catastrophic event, such as a flood, that had destroyed many of the species living in that area. Such regions, he reasoned, were later repopulated by different species immigrating from other areas.

what is gradualism?

The theory that evolution occurs slowly but steadily

Who believed in gradualism?

James Hutton; proposed that Earth's geologic features could be explained by gradual mechanisms, such as valleys being formed by rivers

What is uniformitarianism?

The belief that the Earth's past geological changes can be fully explained by current processes.

Who believed in uniformitarianism?

Charles Lyell; incorporated Hutton's thinking into his proposal that the same geologic processes are operating today as in the past, and at the same rate

what is radioactive dating?

Calculating the age of fossils based on the amount of remaining radioactive isotopes they contain; parent isotope is decayed alongside daughter isoptope

What is a half-life?

It is the time for 1/2 a substance to decay by radioactive processes.

what is relative dating?

method used to determine the age of rocks by comparing them with those in other layers

What does the fossil record show?

a history of the types of organisms that have lived on Earth & the ages of those fossils; new groups of organisms can arise via the gradual modification of preexisting organisms; documents the rise and fall of different groups of organisms over time

What is macroevolution?

the broad pattern of evolution above the species level; Speciation - the process by which one species splits into two or more species. It really boils down to "population" since it is the lowest common denominator in evolution.

what bridges the gap between microevolution and macroevolution?

diversity

what is microevolution?

consists of changes in allele frequency in a population over time

what are some aspects of microevolution?

Gene flow
Genetic drift
Natural selection

What is the morphological species concept?

distinguishes a species by body shape and other structural features; Emphasis is on similarity to a type or ideal specimen; May be used to describe both sexual and asexual species

What is the biological species concept?

A species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with members of other such groups

what is gene flow?

genetic migration between two populations; transfer of alleles between 2 populations, which binds species together

what is the ecological species concept?

Defines a species in terms of its ecological niche - specific biotic and abiotic resources that an individual uses in its habitat

what does the ecological species concept apply to?

sexual and asexual species and emphasizes the role of disruptive selection

what is reproductive isolation?

the existence of barriers that prevent successful reproduction between populations.

What are prezygotic barriers?

block fertilization from occurring by impeding different species from attempting to mate, preventing the successful completion of mating and hindering fertilization if mating is successful

What is habitat isolation?

Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers

what is temporal isolation?

breeding occurs during different periods (day, season, year etc) and therefore cannot mix gametes

what is behavioural isolation?

Courtship rituals and other behaviors unique to a species are effective barriers to mating

what is mechanical isolation?

Morphological differences can prevent successful completion of mating

What is gametic isolation?

sperm of one species may not be able to fertilize eggs of another species

what are postzygotic barriers?

prevent the hybrid zygote from developing into a viable, fertile adult

what is reduced hybrid viability?

Genes of the different parent species (populations) may produce viable offspring hybrids that development or survival in it's environment but are extremely weak and often do not survive; There is a new species in terms of the ones that survive and reproduce - sympatric speciation - the creation of a new species from two existing ones

what is reduced hybrid fertility?

Not able to sexually reproduce i.e. sterile because chromosomes of two-parent species differ in number or structure

what is 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

what is allopatric speciation?

A population forms a new species when geographically isolated from its parent population and gene flow is interrupted when population is divided into geographically isolated subpopulations with barriers between them.

what does the definition of a barrier depend on?

n the ability of a population to disperse; For example, a canyon may create a barrier for small rodents, but not birds, coyotes, or pollen
● Evaporation, flooding, hydrological alterations, abiotic limitation changes

What is dispersal?

can also lead to allopatric speciation and provides opportunity for new isolated populations to form and diverge into new species (selection driven)

What is sympatric speciation?

Occurs in populations that live in the same geographic area
-A population forms a new species without geographic separation.
-Sympatric speciation can occur if gene flow is reduced by factors/mechanisms

what is habitat differentiation?

Sympatric speciation can occur when new ecological niches appear, or when offspring exploit a habitat that was not used by the parents
- Such as a new host, food source, resource allocation, space, competition

What is polyploidy?

The presence of extra sets of chromosomes due to accidents during cell division
-Much more common in plants than in animals
-Can produce new biological species in sympatry within a single generation

what is an autopolyploid?

After a failed mitotic division a tetraploid is formed where 2n chromosomal number is doubled. During meiosis, this leads to gametic doubling of 1n chromosomes but can self fertilize

what is allopolyploid?

A species with multiple sets of chromosomes derived from different species
-Allopolyploids can successfully mate with each other, but cannot interbreed with either parent species

what is sexual selection?

Pick your mate based on expression of some trait leading to speciation - cichlids chose based on food choice mouth parts, depth, color

What is classification?

the process of placing similar taxa within hierarchically nested groups.

what are taxa?

group or level of organization into which organisms are classified

what is taxonomy?

the process of discovering, naming, and grouping similar taxa using biochemical and morphological characteristics.

What is binomial nomenclature?

refers to the two-part scientific name of a species
-The first part of the name is the Genus
-The second part, called the specific epithet, is unique for each species within the genus

what do phylogenetic trees display?

the evolutionary history of a group of organisms is represented by branches

What do phylogenetic trees explain?

patterns of descent, not phenotypic similarity
-Phylogenetic trees do not indicate when species evolved or how much change occurred in a lineage
- It should not be assumed that a taxon evolved from the taxon next to it

what is a shared ancestral characteristic?

a characteristic that originated in an ancestor of the taxon

what is a shared derived characteristic?

an evolutionary novelty unique to a particular clade

what are homologies?

phenotypic and genetic similarities due to shared ancestry

what is ingroup?

a group of closely related taxa that is investigated for evolutionary relationships

What is the outgroup?

a reference group or a taxon outside the group of interest and more distantly related to the ingroup.

What is convergent evolution?

unrelated species evolve similar traits even though they live in different parts of the world

What is divergent evolution?

the evolutionary pattern in which species sharing a common ancestry become more distinct due to differential selection pressure which gradually leads to speciation

what are some examples of macroevolution?

emergence of terrestrial vertebrates through a series of speciation events, the impact of mass extinctions on biodiversity, and the origin of key adaptations such as flight.

what is a mass extinction?

large numbers of species become extinct worldwide.

what is adaptive radiation?

periods of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles, or niches, in their communities.

what role do mass extinctions have on adaptive radiation?

eliminating so many
species

how has the history of life been altered by radiations?

groups of
organisms increased in diversity as they
came to play entirely new ecological roles
in their communities

what are some examples of dispersal?

flying, swimming, walking, or being a passenger on the wind or sea currents

what is vicariance?

when a species' geographical range is split apart by a new geophysical barrier

what are some examples of vicariance?

continental drift, which can form oceans or mountains, climate change, causing ice to melt and barriers to form

what is geodispersal?

the merging of flora and fauna when these barriers fall

what is phylogeny?

the evolutionary history of a species or group of species.

what does each branch point of a phylogenetic tree represent?

an evolutionary lineage

what does the starting branch point of an evolutionary tree represent?

the common ancestor of all the animal groups shown in the tree

what are sister taxa?

groups of organisms that share a common ancestor that is not shared by any other group.

What are some uses of phylogenetic trees?

Infer species identity by analyzing the relatedness of DNA sequences from different organisms.