evolutionary--questions Flashcards
Why is natural selection important in biological evolution?
- -Theorized by Darwin, natural selection refers to the throwing out of less advantageous traits, and ones that increase fitness are kept.
- -The favorable traits are passed to offspring.
- -It allows species to adapt to different environments, the best traits for that environment are kept, while the bad ones lost.
- -It works on the idea that all species have common ancestors, and they have evolved over time, working on Lyell’s gradualism.
- -Natural selection happens to all species, including humans.
- -Natural selection is about keeping up with the environmental stresses.
What is the scientific method and how is it used by many evolutionary anthropologists?
- -The scientific method is really about making a hypothesis, gather info by conducting experiments and making conclusions.
- -For it to be the scientific method, you need to repeat the experiments and have the same results. You can’t conclude this is accepted results until you can get the same result after re-running the experiment many times.
- -Evolutionary anthropology focuses on quantitative data and empirical (can be experienced) data.
- -The scientific method is an empirical approach to collecting data through observation and experience.
- -This field of anthropology is concerned with inheritance and evolution. Since it’s a physical science, the scientific method is used.
What do paleoanthropologists seek to determine in their analysis of the skeletal remains of fossils?
- -They seek to look at the evolution of human and non-human bones. Humans are always evolving, so they want to see the history of human changes.
- -Evolution isn’t linear, but highly variable.
- -For example, “How have our ancestors changed to become what we are today?”
- -They are interested in mechanisms of evolution and inheritance and how we adapt to different stresses.
What is the difference between natural selection and sexual selection?
- -Sexual selection is intraspecific. It has to do with how a female will choose a mate.
- -Depending on if a female needs a mate, there is the possibility of asexual reproduction in some organisms.
- -This is how a female will try to guarantee that here offspring will survive intraspecific competition.
What are the four forces of evolution?
- -Mutation, genetic drift, gene flow, and natural selection.
- -Mutations: The alteration of a gene. They can be point, chromosomal, insertions/deletions, and repeated number mutations. They are the source of variation, they can be good, but usually bad. They can also be deleterious, neutral, or lethal.
- -Genetic drift: The variation of genotypic frequency in small populations. Gene flow is the movement of gene in and out of a population.
What is the chemical composition of DNA and RNA, and what does each do in terms of protein formation?
- -DNA (deoxyribonucleic acid): ATGC; adenine-thymine, guanine-cytosine; also contains phosphates and 5-C base
- -RNA (ribonucleic acid): AUGC; uracil replaces thymine
- -The only role DNA has is that the anti-sense strand is used to code the mRNA.
- -The mRNA is moved into cytoplasm from nucleus in transcription.
- -With a ribosome, a tRNA links the mRNA with amino acids to form the protein in translation.
What is one of the important outcomes of gene flow, in terms of its impact on the genetic variation of individuals within or between populations?
Evolution can occur without natural selection or mutations. Gene flow is simple the movement of individuals in and out of a population. So if an organism that is very fit, their offspring will have a high chance of being very fit as well.
What are the main causes of mutations and how often are they neutral, harmful, or beneficial to an individual?
Mutations are stable changes in the DNA sequence that results in the change of genotypes. They occur in all organisms.
- -Point mutation: When 1 nucleotide is replaced.
- -Nucleotide insertions/deletions: When a nucleotide is deleted or inserted, and the reading frame is thrown off.
- -Chromosomal mutations: Mutations involving the rearrangement of genetic material of multiple genes on separate chromosomes. Sometimes sister chromatids can have uneven sharing of genetic material.
- -Changes in repeated number: This increases the time short DNA sequence repeated. This mutation can result in proteins functioning improperly.
- -We all have genes in us that are neutral but could be lethal. Most of the time, genes are bad, but if they are good, they are passed in the germ cells.
How do we use morphology to characterize strepsirhines and haplorhines?
Strepsirhines: They are characterized by two families, the lemurs and the lorises.
- -Tooth combs, moist rhinarium, unfused mandibular bones and frontal symphases (two bones in forehead), they have reflective eyes, and postorbital bars (bone around the eyes).
- -Lemurs are found in Madagascar and Comoros, are are mostly arboreal quadrapedals. Nocturnal creatures and females dominate society. Varied diets.
- -Lorises are found in sub Saharan Africa and southeast Asia. They are also called galagos in some places. They have 4 legs are are up in trees, and they too have varied diets.
Haplorhines: There are three families associated with Haplorhines, Tarsiers, Platarhines, and Catarrhines.
- -Dry noses, retinal fovea (depression on back of eye that doesn’t allow us to see in dark, but in colors), postorbital close, fused mandibular and frontal symphases.
- -Tarsiers are found in SE Asia and are small (80-130g). They have huge eyes and fused leg bones, and only eat plants.
- -Platarhines are the new world monkeys. They are the cebidaie, atelidae, Callitrchidae. Some have prehensile tails and most are arboreal.
- -Catarrhines are old world monkeys and apes. They are found in Africa, Asia, and SE Asia. They can weigh from 1-175 kgs. Cercopithcedae, Hylobatidae, and Homidae are the genus associated. They have a variety of diets and social interactions.
What are the main processes in primate evolutionary ecology?
There are two: bottom up processes and top down processes. Top down processes occur when there is a removal of a predator which allows animals in lower trophic levels, like plants to grow significantly. These occur when the top predators control the dynamic of the ecosystem. Bottom up occurs when primary producers control the ecosystem. By removing the bottom, those higher up will have crash.
What are some of the complex social lives exhibited by extant primates?
- -Different ranging patterns. The daily path length is the distance travelled in a day. The day range is the area spent in during day. The home range is the area that they call home, and the core range is the area where the most time is spent.
- -They can show deception.
- -They choose who they will mate with. They have different sexual choice and can recognize kin, who is related and who is not.
- -They can become friends with others, and wage ware on groups of dislike.
- -One common characteristic in apes and monkeys are grooming orders. It’s used to strengthen position and resolve conflict. The hierarchy is also maintained by aggression and affiliation.
- -They chose who they eat with and depending on species, males or females will leave the group at maturity which is called philopatry.
What are the main issues in primate conservation?
Habitat fragmentation and disturbance like logging and turning forest into farmland. You have subsistence vs. economic pressures. Its hard to preserve species that are always moving, you cant preserve land, but if they leave, then they are not protected anymore. You have to think of SLOSS.
What are some of the key morphological trends in hominin evolution?
There are many changes in the way human have changed. The forum magnum has moved underneath he head more for bipedal locomotion. Out teeth, especially male, have changed to become less pointy and bladelike and there has been a reduction in teeth dimorphism. There was an increase in brain size, its not because of intelligence, but culturally relevant. We have motor grip and skills and our pelvises are more U like, apes are long and narrow. Our cranial capacity changed about 1.8MYA.
What are some of the morphological features used by early researchers (‘pheneticists’) to suggest that plesiadapids are not primates?
These plesiadapids occupied the Paleocene roughly 67-56MYA. They were tiny and shrew like. They were nocturnal quadrupeds and had a good sense of smell. They were considered primate because they were quadrupeds and were arboreal. They are not actually primates because they have claws instead of nails, their eyes are on the side of the head and they do not have post orbital bars. There is a diastima, space between front teeth and teeth behind.
What are the three main features associated with transitional forms of hominins?
Modifications of postcranial skeleton for bipedal locomotion. Shape and size of canines, especially in males, changes so not pointy or blade like. Reduction in level of sexual dimorphism in canine size. Expansion of brain. A transitional form includes A. ramidus.
