Macroevolution Flashcards
What is macroevolution?
Evolution over geological time of groups larger than 1 individual
Speciation?
Process of how a new species evolves
Biological species
Group of organisms that can reproduce with one another in nature and produce fertile offspring
How do new species arise?
Some members of a species must become reproductively isolated from the rest of the species, when two populations are separated their allele frequency changes. Since they no longer have migration between the population two separate species develop
Allopatric Speciation
When GEOGRAPHICAL BARRIERS divide a population, followed by the development of mechanisms in the separate populations that prevent interbreeding
What is the most important factor in starting speciation
Geographical Isolation
PHYSICAL AND BEHAVIOURAL CHANGES
- develop and keep 2 species isolated from interbreeding… ex. shrimp between the carribean seas have become different species and communicate, collect food, etc. diff.
Reproductive isolation
- formed by geographical isolation
- any factor in nature that prevents interbreeding
(breeding in a close population) between individuals of the same or closely related species
Extrinsic Isolating Mechanism
Outside of the organisms In question EX. GEOGRAPHIC ISOLATION
Intrinsic Isolating Mechanism
Internal characters that prevent interbreeding
Diff in anatomy, physiology, and behaviour
ECOLOGICAL, TEMPORAL, BEHAVIOURAL, MECHANICAL, GAMETIC, HYBRID INVIABILITY
Ecological Isolation
When 2 species have diff habitats they will rarely have contact…
Ex. Lions–grasslands, tigers–forests
Liger- won’t survive in the wild, not meant to exist
Temporal Isolation
- 2 species that share the same habitat but dont mate within the same time grame
- 2 populations of the same species of plant release their pollen at diff time of the year, if their reproductive periods didnt overlap they would’ve reduced gene flow
Behavioural Isolation
- even if populations are in contact and breeding can occur, they must choose to mate
- such a choice is based on SPECIFIC COURTSHIP AND MATING DISPLAYS
Ex. Albatrosses are behaviourally isolated from other bird species by their elaborate species—specific courtship behaviour
Mechanical Isolation
Reproductive organs differ in size/shape/another feature
Diff species of alpine butterflies look similar but have different reproductive organs
Gametic Isolation
Even if mating occurs, offspring may not result if there are INCOMPATIBILITIES between sperm and egg/sperm and female reproductive tract
HYBRID inviability/infertility
Even if offspring develop, they’re most often MALFORMED or STERILE
skip flashcard: for studying tmrw
- why cant hybrids survive and why are they sterile?
(skip)
ALLOPATRIC SPECIES (EXTRINSIC)
Geographic barrier
INTRINSIC
- invariability, eco, temp, gamete, mechanical, and behavioural
SYMPATRIC SPECIATION
Occurs when there are no physical barriers preventing any members of a species from mating with each other and all members are in close proximity to another
- A NEW SPECIES (BASED ON DIFF FOOD SOURCE/CHARACTERISTIC) SEEMS TO DEVELOP SPONTANEOUSLY
Ex. Bacteria developing immunity to sanitizer
How does Sympatric Speciation occur (????CHECK THIS ONE)
Polyploidy
Speciation VIA hybridization
- where the sperm and egg come together and produce an offspring, rarely a healthy hybrid Is produced (FOR TMRW;…WHY?), sometimes successful in plants NOT ANIMALS
POLYPLOIDY
ONLY 4 PLANTS
- multiplication of the normal number of chromosomes In an organism, most happens in self-pollinating plants
WHEN DOES SPECIATION OCCUR
Whenever a group in species isolates and develops unique traits
Generalists VS Specialists
G: can live in diff types of environments, can adapt easier
S: specific diets, especially when food in scarce, must adapt or will die
What does sympatric refer to?
When there is no geographic barrier but these mechanisms continue to work
What is adaptive radiation?
Rapid emergence of species form a single species thats been introduced to a new environment ;; tend to develop niches
Two contributing factors for speciation
Specialization of food sources and environment
Migration to a new environment, especially if there is no competition
Phyletic Gradualism
smaller changes over time
Punctuated Equilibrium
Less gradual changes; spontaneous
What do gradualism and equilibrium have in common?
Depends on their environment, organisms can leave an unsuitable environment for a new one and flourish and pass on genes
Convergent VS Divergent Evolution
Convergent- when species have different ancestral origins but developed similar features (HOMO)
Divergent- 2 separate species evolve differently from a common ancestor (VEST)
