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TTU / Finance / FIN 1402 / What is a group of organisms of the same species living in a particula

What is a group of organisms of the same species living in a particula

What is a group of organisms of the same species living in a particula


School: Texas Tech University
Department: Finance
Course: Biology of Animals
Professor: Jore salazar bravo
Term: Spring 2017
Tags: Biology
Cost: 50
Name: Bio 1402 Midterm 2 study guide/part 1
Description: These notes are a combination of definitions from the book, and topics from the lectures. These notes recap chapter 8-9; however only lectures 10-12. The professor hasn't uploaded lectures 13-15. I wanted to be sure to not miss anything, so I will be uploading a part 2 once he has posted those lectures.
Uploaded: 03/06/2017
6 Pages 41 Views 5 Unlocks

Lauren Berend  

What is a group of organisms of the same species living in a particular geographical region?

Biology 1402  

Midterm 2 Study Guide  

(recap of beginning of ch.8 –mixture of notes from book/lectures)

Chapter 8:  

∙ Population: a group of organisms of the same species living in a  particular geographical region  

∙ Evolution: a change in the allele frequencies in a population  - Evolution doesn’t involve changing the genetics or physical features of  individuals (individuals do not change)

- You change the proportions of the alleles in the population  

∙ Four ways in which evolution can occur:

1. Mutation: an alteration of the base-pair sequence in the DNA of an  individual’s gamete producing cells that changes an allele’s frequency  - Mutations can be caused by high-energy radiation or chemicals in the  environment and also can appear spontaneously  

What is a change in the allele frequencies in a population - evolution doesn’t involve changing the genetics or physical features of individuals?

- The only way that new alleles can be created within a population, so it  is what generated the variation on which natural selection can act  - Despite mutation’s vital role in the generation of variation, mutations  almost always cause early death or lower the reproductive success of  an organism  

2. Genetic drift: a random change in allele frequencies, unrelated to any  allele’s influence on reproductive success  

- Impact of genetic drift is much greater in small populations than in  large populations  

3. Migration: (gene flow) a change in allele frequencies caused by  individuals moving into or out of a population  We also discuss several other topics like What are the different kinds of effectors?
We also discuss several other topics like What is the meaning of hhs?

4. Natural Selection: a change in allele frequencies that occurs when  individuals with one version of a heritable trait have a greater  reproductive success than individuals with a different version of the  trait  

What are the four ways in which evolution can occur?

- Can also be thought of as the elimination of alleles that reduce the  reproductice rate of individuals carrying those alleles – “eliminating the losers”  

∙ Three conditions necessary for natural selection to occur:  1. There must be variation for the trait within a population  2. That variation must be heritable We also discuss several other topics like Based on the goal to predict foot length from forearm length, which variable is the explanatory variable?

3. Individuals with one version of the trait must produce more offspring  than those with a different version of the trait  

- Differential reproductive success: from all the variation existing in a  population, individuals with traits more suited to survival and

reproduction in their environment generally leave more offspring than  do individuals with other traits  

∙ Fixation: genetic drift leads to fixation when an allele’s frequency  becomes 100% in a population. If this occurs, there is no longer  genetic variation for the gene

∙ Founder Effect: a small number of individuals may leave a population  and become the founding members of a new, isolated population  - the founder population may have different allele frequencies than the  original “source” population, particularly If the founders are a small  group  We also discuss several other topics like When was the national woman's party established?
If you want to learn more check out Is a search for knowledge of the natural world?

∙ if a famine, disease, or rapid environmental change causes the deaths  of a large proportion of individuals in a population, the population is  quickly reduced to a small fraction of its original size- this reduction is  called a bottleneck.  

∙ Sexual selection: the natural selection for mating success

- Occurs because of differential investment of energy in constructing an  offspring and caring for it

∙ Fitness: a measure of the relative amount of reproduction of an  individual with a particular phenotype compared with the reproductive  output of individuals of the same species with alternative phenotypes  

∙ Three important elements to an organism’s fitness: 1. And individual’s fitness is measured relative to other genotypes or  phenotypes in the population  

2. Fitness depends on the specific environment in which the organism  lives  

3. Fitness depends on an organism’s reproductive success compared with  other organisms in the population  

- “survival of the fittest” is a misleading phrase because it is the  individuals with the greatest reproductive output that are the most fit  in any population  If you want to learn more check out How do evolutionary psychologists use natural selection to explain behavior?

∙ Adaptation: refers to both the process by which organisms become  better matched to their environment and to the specific features that  make an organism more fit  

∙ Factors that prevent populations from becoming perfect:  1. Environments change quickly- natural selection may be too slow to  adapt  

2. Variation is needed as the raw material of selection

3. There may be different alleles for a trait, each causing individuals to  have the same fitness  

∙ Artificial selection: the process used by animal breeders and farmers,  but the underlying process does not differ from natural selection,  because the three conditions are satisfied  

∙ Natural selection can produce and alter complex traits, including  behaviors  

∙ Traits selected for one function may be co-opted by natural selection  for a new function  

Chapter 9:  

∙ Female: defined as the sex that produces the larger gamete  ∙ Male: produces the smaller gamete  

∙ At conception, the mother’s material and energetic contribution to the  offspring- her reproductive investment exceeds the father’s  ∙ A male’s total reproductive output: the lifetime number of offspring he  can produce, tends to increase as the number of females he is able to  fertilize increases  

- A female, on the other hand does not generally increase her  reproductive success by mating with additional males beyond the first  ∙ Male and female reproductive investment differs across species  

∙ In mammals and many other animals, there are important physical  differences between males and females relating to reproduction.  Fertilization usually takes place in the female. Lactation takes  place only in the female. And in species in which fertilization occurs  inside the female, males cannot be certain that offspring are their  progeny. These physical differences have led to the evolution of  differences in male and female reproductive behavior.  

∙ Two differences between sexual behavior of males and  females:

1. The sex with the greater energetic investment in reproduction is more  discriminating about mating (usually female)

2. Members of the sex with the lower energetic investment in  reproduction compete among themselves for access to the higher investing sex

∙ Differing patterns of investment in reproduction make males and  females vulnerable at different stages of the reproductive process- this  has contributed to the evolution of differences in their sexual behavior

∙ The sex with greater investment in reproduction is more discriminating  about mates

∙ Factors in mate selection:

1. Courtship rituals

2. Control of valuable resources  

3. Gifts up front  

4. Good looks  

∙ Polygamy: a system in which some individuals attract multiple mates  while other individuals attract none  

- Polygyny: individual males mate with multiple females  - Polyandry: in which individual females mate with multiple males  ∙ Monogamy: most individuals mate and remain with just one other  individual  

∙ Behaviors associated with sexual dimorphism:

- One parent invests more in caring for the offspring  

- Mating system tends toward polygamy  

- One sex (usually females) is choosier when selecting a mate  - One sex (usually males) competes for access to mating opportunities  with the other sex  

∙ Behaviors associated with sexual monomorphism: - both parents invest (approximately) equally in caring for the offspring  - mating system tends toward monogamy  

- both sexes are equally choosy when selecting a mate  

∙ In monogamous species, the males and females are similar in  appearance and behavior. In polygamous species, they tend to differ ∙ Sexual dimorphism: the sexes of a species do differ in size or  appearance  

∙ Modes of sexual selection:

- Intrasexual selection: make vs. male  

- Intersexual selection: when one or both sexes are choosy  

∙ Male-male competition:

- combat: competition among males for access to females leads to  elaborate weapons, ornaments, and fighting (antlered flies) - male- male competition is over after copulation, as the male’s mating  success depends on whether his sperm fertilize the female’s eggs  - if a female mates with multiple males, then the sperm from those  males compete for eggs

∙ Sperm competition can lead to:

- Selection for large ejaculate volume (more sperm)

- Mechanisms to prevent other males from inseminating females  - “sperm scrubbers”  

∙ large and small males sometimes use different behavioral strategies to achieve mating success

∙ male-male competition can explain evolution of traits that  promote a male’s competitive ability, even though they may  reduce his survival  

∙ Female choice:  

- Females may actively choose males based on the male’s traits  - A male’s traits may influence his probability of mating—his  reproductive success  

∙ Sexual selection by mate choice:  

- Direct benefits: females choose mates based on the direct, tangible  benefits that they will gain from that mating  

- Indirect benefits: (alleles affecting female mate choice difference in  frequency depending on the fitness of the female’s offspring) 1. Runaway sexual selection: (“sexy son” hypothesis) sons of those  females that choose a male trait have improved mating success  because they inherit the trait that made fathers appealing to their  mothers

2. Good genes: (handicap models) preferred male trait indicated high  viability, which is inherited by the offspring of females who choose  those males  

- the increased reproductive success of these males increases the  frequency of trait and preference genes and reinforces assortative  mating since offspring carry genes for both exaggerated tail length and strong preference  

- when there is a genetic correlation between the male trait and female  preference then the process becomes self-reinforcing  

- Pre-existing bias: (sensory bias): certain traits may be intrinsically  stimulating and evoke greater response – preexisting preferences for  certain traits may be hardwired in females and lead to the  development of exaggerated traits in males  

∙ Caveats to studying human behavior form an evolutionary  perspective:  

- Humans do not consciously do things to increase their inclusive fitness  - Saying a behavior is adaptive does not mean it is morally/ ethically  right

- Saying a behavior is adaptive does not mean it is genetically  determine/developmentally inflexible  

- Not all human behavior is adaptive in modern society – but it could  have been adaptive for our ancestors in recent part (Mismatch to  Modernity)

∙ In pre-industrial humans, polygyny was the norm  

∙ Monogamy is evolutionarily novel in humans  

∙ Childhood is a stage in humans that provides time for the brain to grow (birth to 18 years old)

∙ People had less children the more the more education evolved because less children died at early ages.  

∙ Bi-Parental investment is more likely to evolve in species with helpless  young – the males being more involved  

∙ Adaptive mate preferences in humans:  

- In general, both men and women appear to be choosy when seeking a  long term mate  

- Men should generally prefer women who exhibit signs of fertility (beauty and youthfulness)- the stereotypical male preference for the  female hourglass figure is adaptive  

- Women generally prefer men with features that reflect higher levels of  testosterone (healthier) and better developmental stability (symmetry)  

∙ Are female preferences for male body odor adaptive? Products of major histocompatibility complex play an important role in immune function  - The “smelly t-shirt” experiment

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