Lectures 2-11 Flashcards
Define: phylogeny
The history of the evolution of a species or group
Define: Clade
A group consisting of an ancestor and all of its descendants.
Define:Cladistics
The study of resemblance among clades.
Define: Monophyletic
A taxon that includes the most recent common ancestor of a group of organisms and all of its descendents.
Define: Paraphyletic
A taxon that includes the most recent common ancestor , but not all of its descendants.
Define: Polyphyletic
A taxon that does not include the common ancestor of the members in the taxon
Define: Shared derived character
A character that two lineages have in common, that evolved in the ancestor of a group and is present in all of its descendants e.g. hair on mammals. A shared derived character is unique to a particular clade.
Define: Shared primitive character
A shared primitive character is found not only on the clade being analysed but also on older clades. A character which is not unique to members of that clade.
Define: Outgroup
A species, or group of species that is closely related to the species that we are studying, but known to be less closely related than any members of the study group are to each other.
Define: phylogram
A phenotypic tree that has branch spans proportional to the amount of character change.
Define: Homologies
Similarities due to shared ancestry. These are structures which are similar in organisms that have similar ancestry e.g. the forelimb in mammals.
Define: Analogy
Similarity due to convergent evolution. This comes about when organisms from different evolutionary lineages develop similar structures as a result of the selection pressures of the environment in which they are living. These are not due to shared ancestry e.g. bird wing vs bat wing
Define: Taxonomy
An ordered division of organisms into categories based on their similarities and differences
Info: Homologous genes
2 types of homologous genes, Paralogous and orthologous.
Define: Paralogous genes
Paralogous genes results from gene duplication and are found in more than one copy in the same genome
Define: orthologous genes
Homologous genes that are found in different gene pools because of speciation.
Define: Molecular clocks
Allow for the measurement of the time of evolutionary change. They are based on the observation that some regions of the genome evolve at constant rates. by looking gat the fossil record, your able to deduct when certain species diverged.
Define: Homeoplasties
A character shared by a set of species but which is not present in the common ancestor.
Define: Analogy
Similarity in function and superficial resemblance of structures that have different origins (This is due to convergent evolution)
Define: Evolution
The sequence of events involved in the evolutionary development of a species or taxonomic group of organisms
Define: Catastrophism- cuvier
The theory that the earth has been affected in the past by sudden, short-lived, violent events possibly worldwide in scope. Catastrophism was advocated by Cuvier, Cuvier did not support evolution.
Info: Aristotle
opposed any concept of evolution and viewed species as fixed and unchanging. He viewed species as being arranged on a ladder, with each level being a different species and having the most complex species at the top of the ladder. He believed in Scala nature (‘the great chain of being’ ) essentially he believed that God created each species perfect and therefore there was no need for them to adapt.
Define: Gradualism- hutton
Profound change is the cumulative product of slow but continuous process. e.g erosion due to the flow of a river which will gradually make the river wider.
Define: uniformitarianism
The assumption that the same natural laws and processes that operate in the universe now have always operated in the universe in the past and apply everywhere in the universe.
Info: Darwin
Was profoundly influenced by Hutton’s and Lyell’s observations. Darwin developed two main ideas: Descent with modification and natural selection. Darwin found evidence to support his theory. He believed that species evolved over time and that the earth was much older than previous researchers thought.
Info: Hutton
James hutton perceived that changes in earths surface can result from slow, continuous actions still operating today. Supported gradualism.
Info: Lyell
Charles Lyell used evidence from fossils and buttons theory of gradualism to argue for gradual evolution. He established the idea of uniformitarianism.
Define: Descent with modification
All organisms are related through decent from a common ancestor that lived in the remote past.
How did the theory of natural selection come about?
This theory came about due to 5 observations made by Darwin.
1) If all individuals in a population lived, then population size would increase exponentially
2) Populations tend to remain stable in size
3) Environmental sources are limited
4) Individuals within a population vary extensively in appearance.
5) Much of this variation is heritable
What are 3 important points that need to be remembered about evolution through natural selection?
1) Populations evolve, individuals do not. natural selection occurs through individuals, however changes are seen in offspring, the parent does not evolve.
2) Natural selection can only act on heritable traits.
3) environmental factors vary from place to place, and an adaptation that was selected for in one environment =, may be detrimental in others.
Define: parsimony
Looking at multiple phylogenetic trees and deciding which one fits best in the situation
Define: pseudogenes
Paralogous genes that have lost the function of coding for any functional gene product
Define: Neutral theory
If a population carries several different versions of a gene, odds are that each of those versions is equally good at performing its job—in other words, that variation is neutral: whether you carry gene version A or gene version B does not affect your fitness.
What is a theory?
A set of assumptions, propositions, or accepted facts that attempts to provide a plausible or rational explanation of cause-and-effect relationships among a group of observed phenomenon.
What are extant species?
An extant species is one that is currently existing (i.e. the opposite of extinct)
Define: Innate behaviour
A behaviour which an animal was born with. I.e. an inborn behaviour.
Define: Bottleneck effect
A population bottleneck is a sharp reduction in the size of a population due to environmental events (such as earthquakes, floods, fires, disease, or droughts) or human activities. Such events can reduce the variation in the gene pool of a population, due to the fact that the only alleles available to represent the population would be the ones which survived. Therefore a reduction of Genetic variation occurs.
Define: Founder effect
The founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.
Define: Genetic drift
Random changes in the frequency of alleles in a gene pool, usually of small populations.
Define: evolution
The change in the gene pool of a population from generation to generation by such processes as mutation, natural selection, and genetic drift.
Define: Acoelomate
A solid-bodied animal lacking a cavity between the gut and outer body wall
Define:Adaptation
Inherited characteristic of an organism that enhances its survival and reproduction in a specific environment
Define: Adaptive evolution
Evolution which results in a better match between organisms and their environment
Define: Adaptive radiation
Period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their communities.
Define: Allopatric speciation
The formation of new species in populations that are geographically isolated from another.
Define: Allometric growth
the increase in size of different organs or parts of an organism at various rates.
Define: Altruism
Selflessness, behaviour which reduces an individuals fitness while increasing the fitness of another individual
Define: Amphipathic
Having both a hydrophilic and hydrophobic region.
Define: Analogy
Similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with the same trait.
Define: Anaphase
The fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes ares moving to the poles of the cell.
Define: Antidiuretic hormone
A peptide hormone that promotes water retention by the kidneys
Define: Associative learning
The acquired ability to associate one environmental feature (e.g a colour) with another (e.g a danger)
Define: Behaviour
An action carried out by muscles or glands under control of the nervous system in response to a stimulus.
Define: Bicoid
A maternal gene that codes for a protein responsible for specifying the anterior end in fruit fly.
Define: Biological clock
An internal timekeeper that controls the organisms biological rhythms.
Define: Biomass
The total mass of organic matter comprising a group of organisms in a particular habitat.
Define: Blastocoel
The fluid-filled cavity that forms in the centre of the blastula
Define: Blastocyst
The blastula stage of mammalian embryonic development.
Define: Blastomere
An early embryonic cell arising during the cleavage stage of an early embryo
Define: Blastopore
In a gastrula, the opening of the archenteron that typically develops into the anus in deuterostomes and mouth in protostomes.
Define: Archenteron
The endoderm-lined cavity, formed during gastrulation, that develops into the digestive tract in an animal.
Define: Blastula
A hollow ball of cells that marks the end of the cleavage stage during early embryonic development in animals
Define: Cell cycle
An ordered sequence of events in the life of a cell, from its origin in the division of a parent cell until its own division into two.
Define: cell plate
A membrane-bounded, flattened sac located at the midline of a dividing plant cell, inside which the new cell wall forms during cytokinesis
Define: Coelom
A body cavity lined by tissue derived only from the mesoderm
Define: Coelomate
An animal that possesses a true coelom