Natural selection Flashcards
Evolution
Gradual changes that occur to a population over time
Describes the process where life continues to adapt and survive
Homo sapiens, homo erectus
Natural selection
Process by which organisms that are better suited to their environment than others produce more offspring
Variation in traits
Differential reproduction
Heredity
Charles Darwin
English natural scientist who laid down a framework for the theory of evolution
Darwins finches
Birds on Galapagos island who adapted to fit their surroundings and became so different from the other birds that the became different species
How did Malthus influence Darwin
Darwin was inspired by malthus’ essay on the principle of evolution the theme o which being that population growth would always overpower food growth creating a perpetual state o struggle
Natural selection
Process by which organisms that are better suited to their environment than others produce more offspring
Variation in traits
Differential reproduction
Heredity
Charles Darwin
English natural scientist who laid down a framework for the theory of evolution
Darwins finches
***Birds on Galapagos island who adapted to fit their surroundings and became so different from the other birds that the became different species
How did Malthus influence Darwin/Difference between lamarcks explanation of evolution and Darwin’s
***Darwin was inspired by malthus’ essay on the principle of evolution the theme of which being that population growth would always overpower food growth creating a perpetual state of struggle
How homologous structures show relatedness, examples
when very different animals have bones that appear very similar in form or function and seem to be related.
How vestigial structures show relatedness, examples
once was useful in an animal’s evolutionary past, but that now is useless or very close to useless.
how can looking at emberyos show relatedness
This shows that the animals are similar and that they develop similarly, implying that they are related, have common ancestors and that they started out the same, gradually evolving different traits, but that the basic plan for a creature’s beginning remains the same.
compare human arm to bat’s wing and whales flipper
homologous/humerus, radius,phalanges
how do ear bones give evidence that we have a common ancestor as fish/ how is evolution a conservative process
Humans and other land animals have special bones in their ears that are crucial to hearing. Ancient fish used similar structures to breathe underwater.
what are analagous structures
having the same appearance, structure or function but have evolved separately, thus do not share common ancestor.
Differences between pre and post zygotic barriers to reproduction
Pre- STMGB
Post- VBF
which has a larger impact on speciation, pre or post zygotic factors
prezygotic/allopatric/The formation of two or more species often requires geographical isolation of subpopulations of the species. Only then can natural selection or perhaps genetic drift produce distinctive gene pools.
what is cryptic coloration
coloring that conceals or disguises an animal’s shape
sympatric speciation
Sympatric speciation occurs when populations of a species that share the same habitat become reproductively isolated from each other. This speciation phenomenon most commonly occurs through polyploidy, in which an offspring or group of offspring will be produced with twice the normal number of chromosomes.
allopatric speciation
speciation by geographic isolation, discussed earlier. In this mode of speciation, something extrinsic to the organisms prevents two or more groups from mating with each other regularly, eventually causing that lineage to speciate. Isolation might occur because of great distance or a physical barrier, such as a desert or river, as shown below.
compare natural and artificial selection
artificial-humans choose who reproduces
natural-whoever survives to produce offspring
what is sexual selection, give examples
Selection makes many organisms go to extreme lengths for sex: peacocks maintain elaborate tails, elephant seals fight over territories, fruit flies perform dances, and some species deliver persuasive gifts. After all, what female Mormon cricket could resist the gift of a juicy sperm-packet? Going to even more extreme lengths, the male redback spider literally flings itself into the jaws of death in order to mate successfully.
Sexual selection is often powerful enough to produce features that are harmful to the individual’s survival. For example, extravagant and colorful tail feathers or fins are likely to attract predators as well as interested members of the opposite sex.
polygyny
1 m multiple f
polyandry
1 f multiple m
