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Biology Unit 5 Study Guide

by: Anna Stidham

Biology Unit 5 Study Guide Bio 190

Marketplace > Towson University > Biology > Bio 190 > Biology Unit 5 Study Guide
Anna Stidham
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Ecology and Evolution notes
Intro Biology for Health Professions
Joseph Velenovsky
Study Guide
evolution, Ecology, Biology
50 ?




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This 9 page Study Guide was uploaded by Anna Stidham on Tuesday April 19, 2016. The Study Guide belongs to Bio 190 at Towson University taught by Joseph Velenovsky in Fall 2015. Since its upload, it has received 9 views. For similar materials see Intro Biology for Health Professions in Biology at Towson University.


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Date Created: 04/19/16
Biology Unit 5: Evolution and Ecology Ecology: scientific studies that determine how organisms interact with their environment Biotic and abiotic factors together effect how well organism does in the environment Biotic factors: living parts of the environment (other organisms) Abiotic factors: non­living parts of the environment (nutrients, water) Habitat (niche): specific environment an organism inhabits (includes biotic and abiotic) Levels of organization; Organism: a living thing; studies how they interact with their environment (behavior and  physiology) Genus species name Population: group of individuals of the same species living in a particular region; study  factors that affect the size of population like seed dispersal effect Community: population of organisms living close enough together that they could  possibly interact (all biotic factors in the environment); study interspecies relations Ecosystem: abiotic and biotic factors; study chemical cycles (carbon, nitrogen) and  energy flow between organisms and surroundings Landscape: a collection of ecosystems; study the flow of organisms, materials, and  energy Biosphere: all of Earth that is inhibited by life Biomes: distinguished by predominant vegetation (types of plants present); provide food, shelter, reproductive, and organic material for decomposition; foundation for communities of organisms  commonly found within each type of biome How plants are distributed depends mostly on climate (temp and precipitation)­ similar  climate= similar biome; biological community not specific species Geographically separated biomes look similar b/c of convergent evolution Convergent evolution: similar phenotypic characteristics in independently  evolved species living in similar environments Ex: marine reptile from million years ago looks just like todays dolphin  because they both adapted to living in salt water over time—random  mutations that occurred by chance and took a long time **Do not evolve  to environment** Ex: marsupials evolved a pouch to nourish children not placenta because  they were isolated Within biomes­ patchy vegetation not uniform b/c snowfall ,ay break small tress allowing broadleaf trees such as birch to grow or storms and fires can create these openings as well and biomes are becoming altered by global warming­ snow and ice coverage melting Human alteration of biomes creates species loss Biome types: Tropical forests: warm temp, near equator, lots of sunlight­ long 11­12 hour days, lots of  diverse species Tropical dry forest: scarce rainfall  both have very Tropical rain forest: lots of rain     different plant species Savanna: warm temp, grasses and scattered trees, low rainfall (lots of fires), lots of  herbivores Desert: driest biome and very warm Chaparral: mild rainy winter and v dry hot summer (fires), Mediterranean climate, dense  and spiny shrubs  Temperate grassland: like savannah but no trees and low rainfall Temperate forests: deciduous trees (lose leaves and change color) like oak, birch, maple Coniferous forests (Taiga): evergreen trees like spruce, pine, fir (xmas trees) Tundra: prone to permafrost (ground is permanently frozen); between taiga and polar ice; artic desert Polar ice: very cold and only some mosses and other genera survive Population—have to use same resources, same environmental factors, and are likely to interact  and breed with each other Boundaries of pop are defined based on species ecology and question being asked Population ecology: change in pop size and factors that regulate pop over time; can study  endangered species Exponential Growth Model: (hardly ever occurs b/c necessary to have ideal conditions) New individuals in pop either are born or immigrate// individuals leave by dying or  emigrate Some populations are stable over time like trees in a mature forest but some are very  unstable like bacteria Idealized models determine the size of a particular population Change of population over time and under different conditions G=rN G: growth rate of population (number of new individuals per time interval/net  increase) Growth rate depends on N r: per capita rate of increase (average contribution of each individual to population growth) or (max capacity of individuals with that population to reproduce) Species specific (bacteria­ large r, elephants­ smaller r) but constant N: population size (number of individuals in a pop at a particular time) Hardly ever occurs b/c pops rarely grow in an ideal environment with unlimited space  and resources J­curve­ sow growth when N is small Idealized picture of unlimited pop growth but all populations are limited by resource  availability b/c one or more abiotic or biotic factor will limit population Fur seal: before 1925­ low pop bc hunting but when hunting was controlled  population grew but leveled out in 1935 because of other limiting factors like  space and food Limiting factors: factors that restrict population growth Population introduced to a new environment or rebounding from catastrophic decline­  population size will grow exponentially Logistic Growth Model Idealized pop growth that is slowed by limiting factors as the pop size increases Exponential growth x mathematical expression that describes the effect of limiting  factors on pop size K−N K ) G=rN ¿ K: carrying capacity (max pop size that a particular environment can sustain);  species specific and v dependent on the resource availability; can alter k within  species if in different locations; k is not fixed because biotic and abiotic factors  (temp, food, parasites) will effect because resources are finite ­Outset N is very small compared to K but as population increases N gets  larger and gets closer to K and therefore K­N/K gets smaller At carrying capacity, population has reached max size S curve G=0 flat­lining and K is reached More realistic because it takes in to count the limiting factors Real populations in nature: Population growth will be small when the pop size is either small or large ad highest  when the pop is at an intermediate value in comparison to the carrying capacity; low pop  size­ resources are abundant and exponentially growth occurs; however, the increase is  small because the pop size is small; high pop size­ limiting factors oppose increases in  pop size bc less food per individual or few open reproductive areas so birth rate decreases bc of limiting factors and death rate increases and after a period of time the birth rate and  death rate will equal and so the pop stabilizes at the carrying capacity  Density dependent factors: limiting factors whose intensity is based on population size Results in intraspecific competition­ conspecific (same species) individuals compete for  limited resources; more individuals will be present­ more decline of birth rates­more  competition for food and so not enough food if you have offspring  Humans­ j curve, exponential growth b/c birth # is outweighing death now Advances in nutrition, sanitation, and medical care changed r because death rate  decreased and birth rate was the same—started during early 20  century Lots of researches thought that earth’s carrying capacity was going to be reached because of density dependent factors High pop densities in mice induced high levels of stress and pushed their puberty times  back and depression of immune system—increase in death rate and decrease in birth rate  of mice; crowding affects in mic were also seen in other mammal species 1962­ Growth rate peaked and then from there on birth control and ppl wanted less kids  and formed down­ward trend: demographic transition from high birth and death rate to  low birth and death rate—reduced family size and women are delaying reproduction Mexico—zero pop growth (Spanish flu) Less developed nations­­­ higher rate of increase and reason why exponential rate of  humans is such Age structure: broad base­ large proportion of children and births Population momentum: Population momentum refers to population growth at the national level that would occur even if levels of childbearing immediately declined to replacement level; explains why human population size is still increasing through the rate of increase  has decreased Pop momentum predicts that human pop is going to continue to ncrease to 8 bill  in the next 20 years—do we have enough resources on the planet to sustain 9  billion people? NO the pop in 2025 will need to double the amount of food  present now and agricultural production is already strained and water is already  used 6x over the past 70 years and rivers are drying up; much more land is needed —but take over more land than many species will go extinct Ecological footprint: (resource availability and usage) estimate of the amount of  land required to provide the raw materials an individual or nation consumes— food, fuel, water, housing, water disposal, etc; total area of ecologically  productive land is divided by the global pop each person has like 5 acres (2.1  global hectares); global hectare is the world­average ability to produce resources  and absorb waste; each person takes over 4x what the average is—very large  ecological deficit; US consumption of food and fuel is very high and largest  ecological footprint; our ecological deficit may be just as damaging as the pop  growth itself. If everyone lived the way we do in the US then we would need 4.5  Earths; Recycle and don’t waste food or water or turn lights off Stopping a rapidly expanding population is very difficult and will continue to expand for  several decades even if birth rate is decreased ****Abiotic factors; natural disasters, precipitation, air quality, immigration, temp ****Biotic factors: food, illness/disease, competition between humans; antibiotic  resistance Evolution Charles Darwin­ Galapagos Islands finch’s beak shape based on diet; formulated theory of  evolution—descent with modification; species present today are descendant from ancestral  species: On the Origin of Species delayed publication b/c of religion and someone else in 1858  Alfred Wallace conceived the theory of evolution independently; Wallace sent Darwin his  publication and they came up with the same conclusions­ joint presentation; Darwin published  his book; natural selection accounts for descent with modification Artificial selection­ only allowing individuals with certain traits to reproduce Human­based selective process; all are varieties of a single species Wild chicken and chicken on farms for us to eat are v different All dog breeds came from a wolf at some point; artificial selection is why we have dog  breeds Natural selection­ Observations: Members of a population often vary in their inherited traits All species are capable of producing more offspring than the environment can support Inferences: Individuals whose inherited traits give them a higher probability of surviving and  reproducing in a given environment tend to leave more offspring that other individuals This unequal production of offspring will lead to the accumulation of favorable traits in a  population of generations­ limited resources and therefore only a portion of offspring  survive each generation; only tiny fraction of offspring actually complete development  and reproduce; individuals who have traits that confer the ability to survive food  shortage, disease, finding mates, reproducing are more likely to survive and therefore  reproduce; then these individuals pass these adaptive traits onto their offspring The basis of traits are alleles­ adaptive alleles within a population Natural selection is very environmentally based; traits are advantages only in certain locations Random genetic mutation must occur and that is what natural selection works with Natural selection, evolution, and sexual selection Species: group of individual organisms that can reproduce viable and fertile offspring The number of populations and the number of individuals within each population varies  widely based on geographic location, the life history of the species, and other factors Male donkey and female horse­ mule: sterile and therefore not a species bc not fertile Female donkey and male horse­ hinny; sterile and ^^^^  Evolution: change in the allele frequency within a population/ species over generations Individual organisms do not evolve during their environment Not a single individual becoming accustomed to a new environment Not a change in the physical appearance of an individual Most common level of evolution: natural selection Needed for natural selection­ pre­existing genetic variation Only phenotypic features that are heritable­ only genetic components of variation is  relevant to natural selection FE­ dye your hair will not affect your children bc its not heritable Variation comes from alleles which have mutated randomly Mutation is the ultimate source of genetic variation for evolution Only matters in gametes not somatic cells Mutations that alter protein function are often harmful but rarely a mutant allele produces a  selective advantage to an individual  Occurs way more often when environment changes so that alleles that were once not  advantages are now advantages—rare white rabbit helps in snow climate Chromosomal mutations are often harmful­ errors in meiosis can also account for genetic  variation Mutated repeated segments of DNA can persist over many generations Ancestral mammals has a single odor detecting gene and meiosis errors resulted  in duplication and mice have about 1300 odor detecting genes Prokaryotic mutations can spread quickly—bc they have a short generation time; all haploid so  only one allele so allele has an effect instantly Mutation rate in animal and plants is 1/100000 on average bc of long generation time, low  mutation rate, and diploid genomes prevent most mutations form significantly affecting genetic  within a population or species from one generation to the next—takes a longer time for the effect In sexually reproducing organisms­ unique combination of alleles that each individuals inherits  from mother and father Mutations come from crossing over, independent orientation, and random fertilization Natural selection does not produce genetic variation Natural selection must work with whatever genetic variation exists/ must already  be present Survival of the fittest is ill—more like reproduction of the fittest Genetic variation­ mutation, meiosis, sexual reproduction not natural selection Evolution is not goal directed; will not lead to the perfectly adapted organism; result of  environment to environment; phenotypic characteristics in one environment may be beneficial  but neutral or harmful in a different area; natural selection does not cause beneficial mutations to  occur BONUSES: Sexual selection­ form of natural selection in which individuals with certain traits are more likely than other individual to obtain mates Sexual dismorphism­ females and males look different within a species: in size, forms of  ornamentation, and colors Usually males are more ornamented sex Intrasexual selection­ individuals compete with members of the same sex for mates; physical  combat and displays­ deers running at each other to fight for female; males involved in  competeions and displays Intersexual selection­ females choose their mates based on certain ornamentation Indicator of male quality­ whoever wins is a higher quality male and so female would  want the winner who is more healthy and fit; males that win often produce more  offspring because they win the male; energy for coloration are most fit Seahorses­ males get pregnant­ female gets chosen by size­ reversal of how sexual selection  occurs Handicap signals­ long tail that is hard to live­ if the male can survive with handicap signal must  be high quality male


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