SPECIATION by Ruby

Polyploidy

rubyreedyland — 2014-08-03 23:54:10 UTC

Polyploidy is a condition in which a cell or organism contains three or more times the haploid number of chromosomes. It is rare in animals but more common in all major groups of plants. Natural Polyploidy species occurs in animals among hermaphrodites.

Adaptive radiation

10williab — 2014-08-04 00:03:31 UTC

Diversification among the descendants of a single ancestral group to occupy different niches. The result of a sudden availability of a diversity of niches

Founder Effect

10jerrame — 2014-08-04 00:04:06 UTC

A small group of individuals isolated from the original population may carry a non-representive sample of alleles and evolve differently to the original population. Consequences of founder effect- the separated population may evolve differently from that of the parent population because of different environmental conditions.

Co-Evolution

10williab — 2014-08-04 00:07:12 UTC

One species effects the evolution of another. Results from close interspecies relationships and can produce organisms which are evolved to explicit each other, or to attack or avoid each other. One species evolves in favour of the other mutualistic relationship

Bottleneck effect

10jerrame — 2014-08-04 00:19:49 UTC

Population bottlenecks occur when population numbers and diversity fall dramatically although a populations' numbers may recover often its genetic diversity does not.

rubyreedyland — 2014-08-04 00:20:42 UTC

Genetic Drift

10jerrame — 2014-08-04 00:24:46 UTC

The term for the random changes is allele frequencies that occur in all populations.

Convergent Evolution

rubyreedyland — 2014-08-04 00:26:51 UTC

It describes the process by which species by which species from different evolutionary lineages come to resemble each other because they have similar ecological niches. Analogous structures: having the same structure but still unrelated.

Phyletic gradualism

10williab — 2014-08-04 00:26:57 UTC

Assumes that populations slowly diverge by accumulatingadaptive

characteristics in response to different selective pressure. Gradually changes to different selective pressures.

Natural Selection

Hannahcoak — 2014-08-06 01:55:20 UTC

this is responsible for most evolutionary change, by reducing and changing genetic variation; some combinations of alleles are more likely to help survival and reproduction than others.

Punctuated equilibrium

10williab — 2014-08-06 01:56:04 UTC

daughter species exert powerful selection pressure on each other after speciation

The rate of evolutionary change:

10williab — 2014-08-06 01:57:34 UTC

A new species may form gradually over a long period of time.

Two main models have been proposed for the rate at which evolution occurs: punctuated equilibrium and phyletic gradualism

Types of natural selection

Hannahcoak — 2014-08-06 01:58:05 UTC

1- stabilizing selection- this type of selection maintains the population in a stable form because it favors the average phenotype at the expense of the extreme direction

2- Directional selection- this type favours the phenotype of one extreme over the average or the other extreame, so there is a shift of the average in one direction

Allopolyploidy

10williab — 2014-08-06 02:01:49 UTC

results from mating between 2 species. the resulting hybrid may be sterile. This can cause the organism to have all chromosomes having a homologue with which to pair during meiosis. self fertilisation may then produce a viable, fertile hybrid

Chromosome Mutations

10williab — 2014-08-06 02:21:14 UTC

Large scale mutation can during meiosis, which can fundamentally change chromosome structure.

Deletion: Break may occur at two points on the chromosome and the middle piece of the chromosome falls out. They then rejoin, to form deficient genes.

Inversion: The middle piece of the chromosome falls out and rotates through 180degrees and then rejoins.

Translocation: A piece of one chromosome breaks off and joins onto another chromosome. Then passed to gametes and receives extra genes

Duplication: A segment is lost and added to its homologue.

Allopatric specition

Hannahcoak — 2014-08-06 02:22:26 UTC

Allopatric specition is the divergence of a species after it is subdivided into geographically isolated populations

stage1- moving to new enviroments

stage 2- geographical isolation

stage 3- diffrent selection pressures

stage 4- reproductive isolation

Sympatric speciation

10leeh — 2014-08-06 02:22:42 UTC

Sympatric speciation is the process through which new species evolve from a single ancestral species while inhabiting the same geographic region. Allopatric is more common than sympatric. Speciation through niche isolation and also reproductive isolation

Homologous DNA sequences

rubyreedyland — 2014-08-06 02:23:05 UTC

The relatedness of species can be deducted from the differences in their DNA

Sexual recombination

rubyreedyland — 2014-08-06 02:25:43 UTC

In meiosis cell division, the homologous chromosomes line up in pairs on the equator of the spindle and then move to opposite poles.

Mutation

10williab — 2014-08-06 02:26:59 UTC

The only source of new alleles is by mutations - They are rare and random.

Only the mutations that occur in the information of gametes are passed on to the next generation.

Patterns of Evolution

rubyreedyland — 2014-08-06 02:44:50 UTC