Chapters 45 and 47 work

Derek Lee

Ap Biology

22 January 2010

Chapters 45 and 47 Work

II. Connections

a.       Carrying Capacity and Biotic Potential – In situations that are ideal where there is no predation, lack of vital resources, shelter, food, etc, a biotic potential which is the maximum rate of increase per individual for any population that is growing under ideal conditions occurs. However, in reality, these things to not normally exist in nature and thus the sustainable supply of resources a habitat has will determine the population size. This sustainability of resources determines the carrying capacity, which is the maximum number of individuals of a population that a given environment can sustain indefinitely.  

b.      Organisms of an ecosystem are classified by their functional roles in a hierarchy of feeding relationships called trophic levels. It is basically who its whom and the transfer of energy from one level to the next. Biological magnification shows the concentration of a slowly non/degradable substance in body tissues as it passed along food chains i.e. DDT as it is passed from one trophic level to the next thus also passing down the toxin from one level of animals to the next.

c.       Like consumers, detritivores rely on autotrophs in order to decompose organic matter. Autotrophs capture energy from the sun whom themselves become energy for herbivores, and then consumers. Once plants and consumers die, they begin to decay and their remains become an energy and food source for detritivores.

d.      The mitochondria of living organisms such as plant and humans produces metabolic waste which is released as CO2. Atmospheric molecules of carbon dioxide, water, nitrous oxide, etc are among the main players in interactions that affect global temperature. Collectively these “greenhouse gases” act as pane glasses in a green house which impede the escape of heat energy from Earth into space thus causing the temperature to rise.

III. a. Outline 45.4 Limits on the Growth of Populations

A.    Density-Dependent Limiting Factors

1.      Large and growing populations require a substantial amount of nutrients among other factors to continue to prosper; otherwise risk death

2.      Limiting Factor – Any essential resource that is in short supply.

3.      i.e. food, mineral ions, refuge from predators, living space, absence of pollutants, etc.

4.      One factor alone is often enough to put brakes on population growth.

B.     Carrying Capacity and Logistic Growth

1.      The resources available to a small population of individuals dispersed through a habitat decreases as the population increases in size – growth rate declines

2.      Carrying capacity – the maximum number of individuals of a population that a given environment can sustain indefinitely.

3.      Logistic Growth – shows how carrying capacity may affect population size by changes in growth vs.  number of individuals and unused resources.

4.      When either exponential or logistic growth leads to overcrowding, abiotic and biotic factors function as density-dependent controls – reduce odds for individual survival.

C.     Density-Independent Limiting Factors

1.      Density-independent factors- Any factors that cause more deaths or fewer births regardless of population density.

2.      i.e. availability of a vital resource, exert control after populations become too dense as a result of exponential/logistic growth.

3.      Other factors exert control independently of population density.

b. Summarization of 3 curves & example

1. Type I curves reflect high survivorship until fairly late in life, then a large increase in deaths. For example elephants which give birth to 4-5 calves in her lifetime and devotes several years to parenting each one. Type one curves are similar to human populations where populations have access to good health care services.

2. Type II curves reflect a fairly constant death rate at all ages. They are typical of organisms just as likely to be killed or die of disease at any age, such as lizards, small mammals, and large birds.

3. Type III curves signify a death rate that is highest early in life. They characterize species that produce many small offsprings and do little, if any, parenting. Examples include sea stars and marine invertebrates, insects, fishes, plants, and fungi.

c. 1. The age structure diagram for a population undergoing negative growth would look much skinnier than other graphs, much like the outline of a small fish. Populations experiencing negative growth have nearly equal male-female rations at youth but begin to shift towards females as the population matures.

2. Populations undergoing almost no growth have the shape of the empire state building. The graph is proportional to that of a sky riser that becomes skinnier at the top. The female to male ration remains nearly constant from birth to death.

3. A population undergoing rapid growth has a very large birth growth which consistently becomes smaller at a rapid rate at each level of maturity. By the end of the age graph, the post-reproductive graph is extremely small in proportion to the pre-reproductive years.

4. A graph that grows slowly is very similar to a graph of rapid growth. The main difference is the rate and size at which the graph changes from the pre-reproductive years to post-reproductive years. The graph of slow growth remains more uniform though the changes in age are more subtle. Also, graphs of slow grow have populations which live longer than those of rapid growth which, while growing more rapidly, have populations which also die more quickly.

Derek Lee Chapter 46 and 49 Work/Questions

Derek Lee

Ap Biology

Period 4

Chapters 46 & 49 Questions

Connections:

a.       Co-evolution – Commensalism. Commensalism concerns a close association of two species that benefits one, without benefiting or harming the other (birds nesting in trees or barnacles on whale heads). Co-evolution includes the reciprocal of selective forces of two species on one another causing evolutionary adaptive responses of each species to the other concerning anything from physiology, anatomy, behavior, to life-cycle attributes. If a prey via gene mutation develops more effective defense against predators, its predator via gene mutation will leads to a better way to overcome the prey’s new defense and thus both the predator and prey undergo co-evolution.

b.      Mimicry and aposematic coloration (Warning coloration). Two of adaptations prey’s have developed in response to predators include mimicry and warning coloration whether a creature has both or only one of these traits. Mimicry is the association between one species that is a model for deception for which a different species mimics in form, behavior, or both whereas warning coloration is chemical defense of creatures to use patterns and colors that predators learn to recognize as avoidance signals. For example both mimicry and warning coloration can be seen in with insects that copy the yellow jacket – animals that eat this insect may receive a painful sting – thus predators avoid this insect which in turn protects the mimics’ who defend themselves using mimicry and aposematic coloration.

c.       Natural selection theory helps us develop and test explanations of why some behavior persists and how it offers reproductive benefits that offset reproductive costs associated with it. If the behavior is adaptive, it promotes the individual’s production of offspring. This behavior may be caused by alleles (molecular forms of genes which rise out of genetic mutation) which may give rise to a behavioral trait such as altruism. Altruism in turn requires the self-sacrificing behavior of an individual in a way helpings its’ population produce offspring and ultimately benefit the population.

d.      Individual species which interbreed with one another within a give area give rise to populations. Populations whose species interact with one another and their biotic and abiotic environment ultimately produce a niche which is the sum of the activities and interactions of a habitat as it goes about acquiring and using the resources it must have to survive and reproduce.

1.      Commensalism- Osprey and Sparrow. In commensalism between an osprey and sparrow, the smaller sparrow makes its’ nest beneath/within the nest of the Osprey. Though the osprey does not benefit from this relationship, the sparrow its provided with a home and protection by the larger osprey.

2.      Mutualism – Monarchs and Milkweed. Monarch caterpillars eat the milkweed which in turn kills 2/3 of the population of monarch caterpillars thus fertilizing itself. Meanwhile, the surviving caterpillars receive food and a place to eventually undergo metamorphosis.

3.      Parasitism – Trout and myxobolus cerebralis (protist). This protist causes a whirling disease which damages cartilage and nerves. It weakens the host and causes jaw deformities and whirling movements among other symptoms.

4.      Resource Partitioning – Bristly foxtail, Indian mallow, Smartweed. Resource partitioning among three annual plant species in an abandoned field. The plants differ in how they are adapted to secure soil water and mineral ions. The roots of each species tap into different depths of the soil to reduce competition for resources.

5.      Predator-Prey Co-evolution – Giraffe tongues and thorns. In the predator-prey co-evolution, in order to provide a mechanism to protect themselves, plants evolved to form thorns to protect themselves from being eaten by giraffes or other animals. In response, the giraffe also developed a tougher and more effective tong allowing it to eater the plant even with thorns. As such both undergo co-evolution in order adapt to their prey and/or predator.

6.      Camouflage – Lithops. When this desert plant is not flowering, it looks like a rock. It flowers only during a brief rainy season, when herbivores are more likely to be distracted by the profuse growth of other plants thus protecting itself from the predators.

7.      Mimicry. Yellow jacket model and mimics. There are a few species which deceptively look like yellow jacket wasps but are actually weaponless mimics. All of these mimics strongly resemble a very aggressive wasp that can sting repeatedly, with painful results. This relationship protects the mimics by using the responses of other creature to stay away from the actual deadly yellow jacket model.

8.      Aposematic coloration – Monarch butterfly which have conspicuous patterns and colors that predators learn to recognize as avoidance signals. An inexperienced bird might eat an orange and black patterned monarch butterfly once. It quickly learns to associate the butterfly’s coloration and patterning with foul-tasting toxins, which can poison them.

9.      Pioneer Species – Opportunistic colonizers of new or newly vacated habitats which have high dispersal rates: lichens, club mosses, which have short life cycles, and can survive intense sunlight, extreme temperature changes, etc. They improve soil and other conditions and set the stage for their own replacement.

10.  Keystone Species – Wolves reintroduced to Yellowstone in 1995 has now controlled Elk populations from spending too much time in willows and cottonwoods on river banks. If this did not happen cottonwoods would eventually all have been lost and in turn has sparked the recovery of riparian trees and has stimulated songbird reproduction. They are an example of a species that has a disproportionately large effect on a community relative to its abundance.

11.   Instinctive behavior – Garter snakes which are programmed before hatching to accept slugs as their food source. They perform a behavior (responding to slugs as food) without having first learned it through actual experience in the environment. They are prewired to recognize sign stimuli before being born or hatched.

12.  Imprinting – Goose and baby Geese. In response to a moving object baby geese imprint on the mother goose and follow her during a short, sensitive period right after hatching. They are neutrally wired to learn crucial information such as the identity of the one individual that will be most likely to protect them in the months ahead.

13.  Altruism – Dolphins may support sick or injured animals, swimming under them for hours at a time and pushing them to the surface so they can breathe.

14.  Chemical Communication – Pheromones, signaling pheromones induce the receiver to respond fast, i.e. honeybee calls to action against potential threats or Bombykol molecules released by a female silk moth that can attract males that are kilometers away.

15.  Tactile Communication – honeybee. After locating a source of pollen or nectar, a foraging honeybee returns to its colony and performs a complex dance which signals workers about the general location, distance, and direction of a food source.  

16.  Courtship ritual/display – Australian Redback Spiders – Female spiders (who are much larger than the males) require the males to dance an elaborately choreographed performance for 100 minutes. During the dance, the male joins his web to the female’s and beats on her abdomen in a drum-like rhythm until she accepts him, or denies him where the female spider proceeds to bite off his head and eat him.