Midterm 2 Flashcards
What is biological evolution
Evolution is the change that occurs in the characteristics of organisms in a population over time
Theory of evolution
All modern organisms are related to each other and arose from a common ancestor
Theory of common descent
Modern organisms can be arranged on a “tree” of relationships based on similarities in morphology, development, and genes
modern biological classification system
classifies organisms based on physical similarities between them. supports theory of common descent
How do homologies in characteristics support theory of evolution?
- similarities in the underlying structures of organisms and vestigial structures (i.e. appendix) are difficult to explain except through theory of common descent
- modern data on similarities of DNA sequences match hypothesized evolutionary relationship suggested by anatomical similarities
how do details of embryonic development support theory of evolution
similarities in embryonic development and structures among diverse organisms are best explained as a result of common ancestry
what is biogeography, how does it support the theory of evolution?
the study of the geographical distribution of organisms.
-species that appear related physically are often close to each other geographically
How does fossil record provide direct evidence of evolutionary changes in species over time?
Fossilized remains of extinct species in many groups demonstrate progression of forms from ancient types to more modern types.
Why is theory of evolution considered the best explanation for the origin of humans and other organisms?
- evidence supports hypothesis that organisms have changed over time and are related to each other
- shared characteristics of all of life, universality of DNA and relationship between DNA and proteins support common ancestry theory.
Observations that led to inference of natural selection
- individuals in a population very, and some of this variation can be passed on to offspring
- Not all individuals born in a population survive to adulthood and not all adults produce maximum number of offspring possible
- Survival and reproduction is not random. Adaptations increase an individuals fitness.
fitness
the organisms chance of survival or reproduction
how does natural selection cause evolutionary change?
increased fitness of individuals with particular adaptations cases the adaptation to become more prevalent in a population over generations
examples natural selection leads to evolution of population
- artificial selection (humans deliberately control organisms fitness) causes evolution of different breeds of animals and plants
- populations exposed to environmental changes, in lab and nature, have been shown to evolve traits that give them better fitness
how does natural selection work on allele frequency in a population?
- modern definition of evolution is genetic change in population of organisms
- alleles that code for adaptations become more common in a population over generations as a result of natural selection
why doesn’t natural selection create “perfectly adapted” organisms
natural selection can only act on variants currently available in the population. natural selection makes organism better adapted not perfectly adapted as a result of trade-offs, natural selection does not push in direction of a predetermine “goal”
3 patterns of selection
selection can cause traits in a population to change in a particular direction. However, in some environments it may cause certain traits to resist change and in other environments cause multiple variants to evolve.
why is combination drug therapy an effective tool to combat drug resistance?
- disease causing organisms can evolve resistance to antibiotics because they consist of multiple variants that have differential survival when exposed to various drugs; evolve drug resistance through natural selection
- mutant organism that is resistant to several different antibiotics is relatively unlikely so combination therapy can reduce risk of antibiotic resistance evolving
- as a result of trade-offs, varieties of disease causing organisms that are multiple drug resistant are less likely to survive and reproduce under normal conditions than are non resistant varieties. resistant organisms are therefore less transmissible than nonresistant varieties.
define biological species
a group of individuals that can interbreed and produce fertile offspring. Biological species are reproductively isolated from each other, thus separating the gene pool of species.
Reproductive isolation
maintained by prefertilization factors such as differences in mating behavior or timing or post fertilization factors such as hybrid inviability or sterility
describe 3 steps of speciation
- populations of a species become separated from each other
- populations diverge from each other and reproductive isolation between populations evolves
explain how “race” in biological species can be defined using genealogical species concept
biological races are populations of a single species that have diverged from each other but have not become reproductively isolated.
list evidence that modern humans are young species that arose in Africa
- morphology of human ancestors in fossil record provides evidence modern species is app. 200000 years old
- genetic evidence indicates modern humans have limited genetic diversity a characteristic of young species and that the oldest populations (containing most genetic diversity) are found in Africa
How is Hardy-Weinberg theory used in studies of population genetics.
- Provides a rule for calculating allele frequency from genotype frequency
- if the assumptions of Hardy-Weinberg (no natural selection, no migration, and random mating of individuals within a population) are violated, allele frequency will not match expectations
evidence human races are not deep biological divisions within human species
- modern humans do not show evidence they have been isolated from each other long enough to form different races.
- other genetic evidence indicates that human groups have been missing for thousands of years.
traits that have become common in certain human populations due to the natural selection these populations have undergone
similarities among human populations may evolve as a result of natural selection. sickle-cell is selected for in populations in which malaria incidence is high and light skin in areas where UV light level is low.
define genetic drift
changes in allele frequency due to chance events such as founder effects or population bottlenecks
sexual selection
individuals, typically females, choose mates that display “attractive” quality, may be responsible for creating differences in human populations
positive assertive mating
individuals choose mates who are like themselves, can reinforce differences between human populations
Number of species estimated and why it is an estimate
estimated between 1.4 and 1.8 million. could be as high as 100 million
list three major domains of life
-bacteria: share common ancestor with archaea and eukarya while last two groupe are more closely related. Bacteria and archaea are prockaryotic organism without a nucleus or other membrane bound organelles. Eukarya are eukaryotes
endosymbiotic theory for the origin of eukaryotic cells
eukaryotes, cells with nuclei and other membrane organelles, probable evolved from symbioses among ancestral eukaryotes and prokaryotes
for major kingdoms of eukarya
Protista, animalia, fungi, and plantae
adaptive radiation
occurs when several new species appear quickly after the evolution of a new “way of life” or the death of a competing group.
-diversity of flowering plants may be due partly to adaptive radiation resulting from their production of defensive chemicals
virus
viruses are non living entities made up of genetic material in a transport container and can reproduce only by high jacking living cells
algae
protists that store food and thus are targets for predators. Make defensive chemicals against predators.
fungi
compete with bacteria for food. produce antibiotics
how are evolutionary classifications of living organisms created
phylogenies are created and tested by evaluating the shared traits of different species that indicate they shared a recent ancestory
epithelial tissues
epithelia line and cover organs, vessels, and body cavities. Tightly packed tissues with one free surface. Outer growths of epithelia form some glands. These tissues function in protection, secretion, and absorption.
6 types of connective tissue
loose tissue, adipose, blood, fibrous connective tissue, cartilage, bone tissue
loose connective tissue
connects epithelia to underlying tissues and holds organs in place. cellular component is fibroblasts, matrix rich in proteins, collagen, elastin which provide tensile strength and elasticity
adipose
connects skin to underlying structures and insulates and protects organs. cells synthesize and store fat and have little extracellular matrix
blood
type of connective tissue that transports oxygen and nutrients to body cells. Blood cells have a liquid matrix called plasma.
fibrous connective tissue
forms the tendons and ligaments. cells are fibroblasts and matrix is rich in collagen.
cartilage
flexible, shock-absorbing tissue composed of cells called chondrocytes that secrete a dense, collagenous matrix
bone tissue
provides support for the body. cells are called osteocytes and the matric is rich in collagen and minerals