Speciation Flashcards Preview

Biology Definitions > Speciation > Flashcards

Flashcards in Speciation Deck (63):
1

Biological Evolution

"The genetic change in a population from one generation to another"

2

Species

"A group of organisms that interbreed to produce fertile offspring"

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Speciation

"The formation of a new species, the result of reproductive isolation"

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Population

"Members of the same species that live in the same geographical area"

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Deme

"A local population that has no or limited gene flow with members of other population"

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Cline

"When a species has an extended geographical range, variation may occur along a gradient from one point of the range to another point"

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Ring Species

"When the two ends of a cline join to form a loop or a ring"

8

Gene Flow

"Movement of alleles carried by individuals between populations"

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Genetic Drift

"A change in allele frequency due to the accumulated effects of chance over successive generations"

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Founder Effect

"When a small number of individual animals found a population with only a small proportion of the 'parent' population"

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Bottleneck Effect

"Occurs when a large population is suddenly reduced due to a catastrophic environmental event, and allele frequencies are randomly altered"

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Inbreeding

"Inbreeding increases chances of favourable alleles coming together and results in desirable phenotype"

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Outbreeding

"Outbreeding tends to increase the number of heterozygous in a population and decrease the chances of harmful alleles coming together"

14

Natural Selection

"The process in which inheritable traits that make an individual more likely survive long enough in its environment to reproduce become more common in the population over successive generations"

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Selection Pressure

Environmental factors which influence individuals survival"

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Disruptive selection

"Individuals at both extremes of distribution are selected for simultaneously"

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Stabilising Selection

"Extreme phenotypes are selected against, and average phenotypes are selected for"

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Directional Selection

"A single phenotype is selected for and the allele frequency continuously shifts in one direction"

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Sexual Selection

"Males (or females) compete for partners, with the heritable characteristics of the 'winners' being passed on"

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Phylogenetic Trees

"Evolutionary trees drawn as a branching diagram which shows inferred evolutionary relationships between taxa"

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Mutation

"A sudden, permanent change in the genetic material@

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Missense mutation

A missense mutation produces an altered protein

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Nonsense Mutation

A stop codon results in the early termination of protein synthesis

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Beneficial Mutations

Increase an individuals fitness

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Deleterious Mutations

Decrease in an individuals fitness

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Ploidy

Refers to the number of chromosomes in a cell

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Genome

The entire complement of genetic material in an organism

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Haploid

The number of chromosomes in a gamete, n

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Diploid

The number of chromosomes in the zygote, 2n

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Monoploid

The number of chromosomes in each set, can be same as haploid

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Aneuploidy

Only certain chromosomes are represented an unusual number of times

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Monosomy

Only one chromosome is present instead of two

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Trisomy

Three copies of the chromosome are present instead on two

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Tetrasomy

Four copies of the chromosome are present instead of two

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Polyploidy

Every chromosome is represented 3 or more times

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Autoployploidy

Involves the multiplication of an entire genome within a single species

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Non-disjunction

The spindles do not function properly and so the chromosomes are not separated

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Allopolyploidy

Hybridisation between species and the chromosomes in the offspring were doubled producing fertile seeds

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Speciation

The formation of a new species as a result of reproductive isolation

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Sympatric Species

Closely related species that live in the same geographic location

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Allopatric Species

Closely related species that live in different geographic locations

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Geographical Isolation

Results from physical barriers separating populations

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Structural Isolation

Results from the fact that the differences in structure of the external reproductive organs do not allow transfer of sperm between the sexes

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Ecological Isolation

Results from differences in habitat within the same geographical area

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Temporal Isolation

Results from breeding behaviour occurring at different times

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Behavioural Isolation

Results from differences in behaviour, typically courtship

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Gametic Isolation

Results from incompatibility of gametes

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Hybrid Inviability

The offspring is inviable (unable to survive) so dies in early development

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Hybrid sterility

The hybrid reaches maturity but is infertile so cannot breed

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Hybrid breakdown

The hybrid produced is fertile but it's offspring are infertile

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Allopatric speciation

When a population is divided into two or more geographically isolated populations and new species are formed

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Sympatric Speciation

One species give rise to two or more species without prior geographical separation

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Instant Speciation

As a result of polyploidy

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Fossils

Preserved remains left by organisms that lived in the past

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Biogeography

The study of the geographic distribution of species

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Vicariance

Large scale allopatric Speciation by a significant geophysical event

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Gradualism

New species could evolve with a gradual transition from one form to another

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Punctuated Equilibrium

The formation of many different species that are no longer closely related

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Divergence

When two or more species result from a common ancestor

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Adaptive radiation

Involves the rapid evolution of a large number of species from an ancestral group to occupy a variety of different ecological niches

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Convergent Evolution

Two or more unrelated species evolve to resemble each other as a result of similar selection pressures

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Parallel Evolution

Occurs when two or more unrelated groups evolve along similar lines

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Co-Evolution

Reciprocal evolutionary change in which a feature of one species acts as a selection pressure for a change in a feature in another species, but both species have a strong ecological relationship