Nov. 28, Human Behavior

How does natural selection apply to humans? The fields of Biology and Psychology diverged instead of coming together as Darwin once thought they would.

John Broadus Watson symbolized the behaviourist approach and that psychology should not concentrate on its concern with unobservable entities such as minds and feelings. Both animals and human psychology should abandon any reference to consciousness and stess the importance of environmental conditioning. Watson was in opposition with Darwin and was very anti-evolutionary and anti-hereditarian when it came  to human behavior.

William James looked at animals for the instinctive roots of human behaviors and morality and noticed they were modified by experience. Francis Galton associated the ideas of heredity and instinct with dangerous political thoughts. They misinterpreted the science and used it to their advantage. The thoughts such as, care for the sick and needy led to the procreation of the less fit, gives a crazy outlook on behavior. The thought was brought up that the STATE should INTERVENE to modify human mating choices. The eugenics movement was born from these thoughts. This lead to some practiced in the United States such as compulsory sterilization and restriction of immigration.

Evolutionary Psycology thought that there was an environmental connection to evolutionary adaptiveness and that module-based capabilities in the brain evoled. Nearly all sociobiologist and evolutionary psychologists now assert the psychic unity of mankind, regaurdless of race or ancestry all human’s cognitive make up are the same, are not our of political correctness.

Evolutionary Pschology versus Human Behavioral Ecology/Sociobiology

What is the Modular Brain Concept? It is the differenct components of the brain deal with different specific functions, such as, vision, hearing, talking. Perceptual modules operate quickly, immune from interference by memory, experience or reflection.



Nov 10; Plant Communication and Behavior

Plant communication and behavior relies on phenotypic plasticity. Plants are unable to run away, they have to live with the consequences of their behaviors.

The various cues that a plant recieves can affect a number of things including, shoot phenotype and root development. How do plants respong to shading, shade from their own leaves and shade from others?

They either confront, avoid, or tolerate. When a plant confronts a competitor the plant will have an elongation response, and increase apical dominance. When a plant avoids a competitor the plant will grow away from the competitor or have dependent germination. When a plant tolerates a competitor it will just be tolerant to the shade morphologically and physiologically.

How do plants perceive light levels and wavelengths? They possess photoreceptors, phytochromes, crytochromes, phototropins, and some unidentified UVB sensitive to particular wavelengths.

Plants can tell the difference between being in the shade of a building or a rock, versus shade of another plant. This is because of the different wavelengths of light that are absorbed by other objects. Red light is absorbed by plant canopy, far-red isn’t. That means a plant with full sun is being exposed to different ratios of red and far-red wavelengths opposed to plants which are being shaded.

Shade avoidance is a collection of responses to vegetative shading. Plants can anticipate and respond to future shade. Plants elongate less when wearing a collar that filters out far-red light reflected from adjacent leaves. Another example of this is Portulaca oleracea, or common parsalin, grows and branches in a wa that minimizs self-shading. When lower red/far-red ratios occuring in one direction the plant grows away from it.

Shade tolerant species tend to be very slow growing. The differences in allocation cause long-lived shade-tolerant plants that invest relatively more resources into defense against herbivores and pathogens.

Ligh information is more than just quantity and spectrum. It is likely that plants respond to a richer range of light cues. Vertical, mid-day shade might indivate a very tall neighbor where the plant would not want to compete to grow larger. Horizontal and late-day low r:fr cues might indivate similarly sized neighbors where the plant would compete with its neighbor.

Somatic Competition happens when plants compete with themselves. There are many redundant organs that compete with each other. In “Somatice Competition” the plant can increase performance by putting more resources into more successful organs. The growth rate can vary. Experimental evidence supports the 3 types of responses; independant, cooperative, competitive.



Nov. 8th; Plant Development and Hormones

Male Gametophytes:  Pollen

Female Gametophytes: Embryo Sac

Generative Cell will divid to become the two sperm. The tube cell makes up the pollen tube into the pistil of the plant.

One sperm fertilizes the egg, the other will fuse with the polar nucei. The fertilized egg will become the embryo. The two polar nuclei and sperm will be the endosperm that provides nutrients to the embryo. This is known as Double Fertilization.

Embryo Development

The last step of seed development is that they become desiccated, they only have 5-20% water. The seeds coat will harden.

Inside of the seed will be the seed coat, the radicle (embryonic root), Cotyledon, Epicotyl (above cotyledon), Hypocotyl (below cotyledon).

Cotyledon are seed leaves that are packed with nutrients. In monocots, the cotyledon will wrap to become the Coleoptile.

Plant Hormones

Five Main Classes of Plant Hormones

The five hormones: Auxin, Cytokinins, Gibberellins, Ethylene, Abscisic Acid

Other Plant Growth Requlators: Salicylic Acid, Jasmonic Acid, Systemin

Working with Coleoptiles Charles Darwin and son Francis studies phototrophism. They found that cutting the tip prevents it from bending. They put an opaque cap on the tip and it did not bend. If covered with a clear cap it did. If they covered the bottom with a cap it still bent. This means that there was a signal from the tip of the plant that must have been responsible for this phototrophism. Peter Boysen Jensen took it a step further and studied the chemical signal. Fritz went isolated the chemical responsible for the signal. This chemical was an AUXIN.


This is a the first plant hormone discovered. It is the Greek word for increases. Natural auxins consist of things like indole acetic acid (IAA) and relate to molecultes. They are produced in the apical meristems of shoots. They are usually transported from the top down, basipetal transport. This gradient become really important.

The process in which auxin phototrophism occurs is the ACID GROWTH HYPOTHESIS. Auxin increases proton pump activity. The cell wall becomes more acidic, and unzips the hydrogen bonds. This makes the wall soft allowing turgor pressure to push cell wall outward.

Auxin is also involved in gravitrophism. The starch-statolith hypothesis is an explaination of gravitrophism. The amyloplasts, leucoplasts that store starch, are used to figure out what is up and what is down. Whe the weight of the amyloplasts hit it triggers auxin production. Auxin is produces in the shoots.

Auxin is really important for apical dominance, tissue differentiation, lateral roots, fruit development, leaf abscission, and herbicide. In tissue differentaitaion, if you damage the vascular tissues, auxin initiates formation of vascular tissue to heal the wound. Auxin stimulates pericycl cells to divide.  The auxin enhances fruit growth, developing seeds are the source of IAA. The absicssion, or dropping of leaves and other plant parts, are a cause of a drop in auxin that drops the part. Synthestic auxins are used as weed killers.


Johannes van Overbeek discovered that coconut milk possessed factors that accelerated the growth of plant embryo and isolted tissues and cells in test tubes. 

They are found in actively dividing tissues, cytokinesis. The are shown to cause plant cells to grow in an undifferentiated mass of cells (callus). The combination of auxin from above and cytokinin from the root tell the tissue what to differentiate into. Cytokinen is produced from the roots. They can delay and reverse senescence (the process of ageing) in plants. They release buds from apical dominance.


E. Kurosawa was working on the disease of rice that produced fast growing, pale-colored and sickly plants. This was caused by a fungus isolated from the rice and later bean plants. The bean plants showed gibberellins were being released from the plant itself instead of the fungus.

Gibberellins are all about stem elongation. Dwarf plants are a varity of mutations that cause a lack of gibberellins or the inability to process gibberellins. Bolting, or the sudden verticle growth associated with flowering and death, is mediated by gibberellins. There is a spike in the gibberellins concentration. They are also really important for germination.  Gibberellins will induce genes to make enzymes that break down starch in the remaining endosperm. The biggest current use of gibberellins today is in Thompson’s seedless grapes.

Abscisic Acid

Abscisic acid causes stomatal closure, and prevents premature germination of seeds. It is very important for water regulation.


Ethylene is a gas that was discovered by accident by citrus growers. They noticed that if they kept them in a warm shed they could ripen the fruit faster. Ethylene gas hastens the ripening of fruits. It is importatn in seed germination, fruit ripening, and absission.




Oct 27; Coevolution

What is coevolution?

Coevolution involves two or more species which exert selective pressures on each other and evolve in response to each other.

The key idea is because each species involves in response to each other the selective environments is constantly changing.

When does coevolution occur?

Selective pressure will be strongest when there is a close ecological relationship. Close relative in terms as species who are specialists rather than generalists.

How do we study Coevolution?

There are different levels that we look at coevolution. The study of adaptations of the individuals, interactions between species or broad evolutionary patterns.

Does coadaptation demonstrate coevolution?

Some biologist would say that having coadaptation does not give evidence to the parallel evolution between taxa. To convincingly show coevolution you must show a parallel evoltuion between taxa.

An example of this would be the Fig Trees and Fig Wasps.

The figs have a specialist relationship with the wasps. The wasps act as pollinators for the figs. Coadaptations happen with these species. The receptive figs produce scents that are specific to a particular pollinator species. The shape of the ostiole is specifically shapped to the head of the particular wasp species. The morphology of individuals flowers specialized to a particular wasp species.
The Fig starts to develope and the ostiole opens up. The female wasp crawls in and lays here eggs in the plant with pollen from the fig she was born from. The eggs hatch and the females fly out and find another fig.


Congruent phylogenies due to cospeciation is strong evidence for coevolution.

Oct. 27, Seed Dormancy and Seed Banks

Seed dormancy means that seed is in a state of suspended growth and development. This is a reduction in the metabolic rate. This gives resistance to adverse environmental conditions.

The conditions that must be present to break dormancy differs by species. Some species germinate as soon as the environment is suitable for growth. Other species need something else such as; An intial drying period, exposure to a long period of cold, scarification of the seed coat, or intense heat.

There are possible selective advantages to these cues to break dormancy. The cue for long periods  of cold are advantagious for species because of long winters.

Different species of plants produce seeds that require different cues to grow. A seed bank is produced by the different speices’ seeds waiting for these cues. A seed bank is a collection of dormant seeds in the soil. Seed banks allow dispersal in time as well as space.

There is a broad inverse correlation between the lifespan of adult plant and longevity in the seed bank. Annual plants will tend to have seeds that last for a long time . The storage effect is a model that shows the environment varies over time, and different species respond to the environment each year. An environment good for one species may not be good for another species. As long as the species has atleast one tough life storage stage that can get you from one good year to another good year this prevents the population from crashing. Populations stores up the good years to make it through the bad ones.

Long lived seeds do not need long live matured plants, but long lived matured plants do not need long lived seeds.


Oct. 26; Proximate and Ultimate Causation

Why do people like candy?

Because it tastes good! Most people have a taste for sugar. Well, why do we like sugar? Physiologically we can answer that question by looking at the receptors to the brain. The neurological path tells us that this tastes good. This is a mechanistic reasoning.

These questions can be answered proximatly, the here and now, or ultimate, evolutionary history. The proximate analysis deals with how genetic-developmental mechanisms inflluence the assembly of an animal and its internal components. Proximate analysis also deal with neuronal-hormonal mechanisms which develop within an animals lifetime that control animal behavior. The ultimate analysis deals with evolutionary history of a species and their adaptive values.

The Ultimate Analysis

The selection and adaptation of a species will determine the cause for certain behaviors such as manogamy. In Praririe voles, the evolution history shows that their decendants were first polygynous, but their manogamy developed overtime. This could probably be due to female sparceness.

The Proximate Analysis

At the proximate level we look at the hormonal-nervous system mechanisms. In Praririe voles, bonding of vasopressin with receptors triggers chemical activies that affect neural pathways. This provides the males with positive rewards. The rewards cause males to stay near one female. It is a proximate cause for manogamy.

The Proximate Mechanisms

The mechanisms of proximate causes include neurophysiology and genetic activity. The key sensory, environmental, inputs must cause some gene activity and produce changes in biochemistry. The biochemistry alters neurophysiological mechisms that lead to learning.

What are the Advantages and Disadvantages of Learning?

The disadvantage of having to learn a skill is that it takes a lot of time and energy. This lengthen the time it takes to be ready to do the actions this skill requires. The time, energy, and neuromechanisms used for learning means you can’t use those things for other activities.

The advantages of having to learn a skill are vast. These advantages inclue being able to match the skill to the social environment.

Nature vs. Nurture

The development of and organism is an interactive process. The genes and environment is continually interacting throughout the lifespan of the organism that cause changes. The genetic information interacts with changing internal and external environments. The genes are either turned off or on by signals. These signals are internal, cellulcar, chemical or external environmental stimuli. The interactions alter the assembly of the organism, its neural network, as well as other aspects of its physiological or anatomical systems.




Oct. 24; Reproductive Control

In this class we take a look at the reproductive control males and females try to have over the fertilization of eggs. These topics are varied and vast.

Sperm Competition

Sperm competition is more actively controlled by the animal that is involved. There is a variety of ways that males and females try to have the upperhand in fertilization. This occurs in insects, birds, and a variety of other species.
Males and Females can remove sperm from individuals. Some females will store sprem and control which sperm is fertilizing their eggs.

Mate Guarding Males

Males will gaurd the female, so that they will control female permiscuity. If a male can gaurd another male’s access to the female, then they can be sure their genes will make it into the next generation.

In spiders there is a step up from this mate guarding. Male spiders will produce sperm in their abdomin and use a petipalt to transfer the sperm to the female. The female will store the sperm. The male will break the palp off and it will act as a plug to the females sperm storage area.

Nuptial Gifts

This brings up the idea if females are choosing mates on quality.

Key ways the Males and Females try to Control Reproductive Decisions

Female Control: Egg investment, Mate Choice, Egg Fertilization, Offspring Investment

Male Control: Resource Transferred to Female, Elaborate Courtship, Sexual Coercion, Infanticide.

Sexual Cannibalism

Some species, one sex consumes the other sex. In sexual cannibalism, there is a subgroup of sexual suicide. The female gets a nurtitional resource. The short length of their life and the small chance of finding a mate leads to a reason why this sexual suicide makes sence.

Good Parent Theory

Females prefer to mate with males that provide more paternal care. Male courtships is linked to his parental abilities. (15- spine stickleback)


When we look at species with ornamental features the question that is brought up is do these ornamental features mean good genes? Is the male healthier? In some species, we see there is a correlation between the beauty of the ornamental feature and offspring health, but this is not always the truth. This is runaway selection. Runaway Selection is an evolution sensory bias of the female the excentuates the feature.

The female mare choice genes and the genes for the prefferred male attribute are inherited together. The daughters inherit the genes for the mate preferencec, and the sons inherit the preferred attribute. The males attract more females with the preference, and the mate preferrence takes on a life of its own. Even when the male do not have the best genes.

Chase-Away Selection Theory

This theory is explained by sensory exploitation. The initial sensory exploitation is started by the viability selection on female sensory systems. The female attration for a male trait from a preexisting bias. This mutation produces a rudimentary male display trait to exploit the females preexisting bias.

The females fitness declines due to this change, so the female mating threshold increases. The male attraction decreases, so the male attractive trait increases and this becauses a circle.

Sexual Conflict

There are a variety of ways that sexual conflict that can occur between males and females.

Oct. 12; Foraging and Sexual Reproduction

In this class we discuss the different aspects of foraging  and sexual reproduction in the animal kingdom.

Foraging Behavior

Aposematism is a coloration of an individual that repels predators. The formation of this color repellent was able to evolve because the individual who was wounded did not die, but was not eaten. This individual was able to pass on its genes. The predator also needs to be able to remember that the color mean toxic.

Optimal Foraging
In optimal foraging you are going to get the most amount of food for the least amount of energy. This also increases the energy available for reproduction. The optimal foraging theory predicts than an animal should behave in a way that maximizes the benefits, minimizes the costs, and in turn will maximize the net energy gain.

We can look at various species to see if they are foraging optimally. The main thing that could determine the ability to forage optimally is the present of a predator. This will push the individual into a sub-optimal environment.

Profitability of Prey
Profitability of prey is the energy gained per unit of handling time. An example of the reduction of optimal foraging is seen in young garden skinks. Their foraging success is lowered in order to reduce the risk of predation. When the number of there are predators sensed there are a smaller number of active lizards, but when you have coverage by a micro-habitat the percentage of lizards that are active increases.

Alternative Foraging Strategies

Frequency-Dependent Selection
Frequency-dependent selection is genetically based strategy. As the percentage of a prey species with a specific trait increases overtime it will be consumed more of the time. The predator will eat the more common morph. So, overtime as the the abundance morph will start to decrease, and the other morph will increase. The genotype with a rare genotype is less likely to be consumed. As oscillation of  morph frequency will become apparent.

The percent frequency of a blue morph butterfly is larger than an orange morph butterfly. As the more abundance blue morphs are being predated upon, the orange morph will produce more offspring and become more and more frequent. The blue morph becomes more rare because of predation, and the orange morph is more frequent. The predator will then consume the more frequent orange morph. The blue morphs will then be able to reproduce more while the orange morphs are being killed. The occilation of morph frequency starts to appear.

Conditional Strategies
Conditional strategies are an inherited mechanism that give the individual the ability to be flexible. The foraging strategies shift from being a predator, competitor, scavengers or commensals. The behavior depends on the environment, but the mechanism to be flexible is genetically inherited.

Geographical Separation/Divergence

The Evolution of Reproductive Behavior

Sexual Selection
Sexual selection involve traits that lower survival, but enhances the ability to mate. Sexual selective traits are anything that increases the chance of an individuals getting their genes into the next generation based on their ability to mate. The trade off with the increased ability to mate is with its survival ability. The traits can increase their chances of being predated on, decrease foraging ability, ect.

The variation in reproductive success is greater for males than for females. There are a few individuals who get most of the mates, and many individuals who never mate or mate infrequently as a male. The female do not vary as much in how many times they mate, or how many mates they have. The theory of the variation between males and females are the cost of their gametes. The female have fewer and less frequent production of the egg, and at a higher energy cost. The males produce many sperm and will mate with many individuals. Females will be choosy. This produces a conflict between males and females, the operational sex ratio.

Operational Sex Ratio
The actual sex ratio in the field is 50/50 between males and females, but the operational sex ratio tend to be heavily male biased. That means there are a lot more males running around that are sexual active. The females, once their eggs are fertilized, will stop looking to take care of their egg. This male biased ratio is very common.

The operational sex ratio can be reversed where the ratio is heavily female biased. This can occur when males are focused more on other survival behaviors like foraging.


Oct. 11; Sexual Reproduction

Sexual Reproduction in Plants

Alternation of Generations
Alternation of generations is when you have life history that alternates between free-living multi-cellular diploid stage (sporophyte) and the free-living multi-cellular haploid stage (gametophyte).

Image result for alternation of generations
“Diagram showing the alternation of generations between a diploid sporophyte (bottom) and a haploid gametophyte (top)” Retrieved from Wikipedia Article on Alternation of Generations

Alternation of generation can be applied to green algae. In the case of Ulva, the gametophytes and the sporophytes look exactly the same. This is call isometric alternation of generation. (Iso = same)

The general trend is to have sporophytes be the more common stage of reproduction. However, with moss this has not happened.

Alternation of generation can be applied to mosses. The sporophyte grow above the female moss.

Alternation of generation can be applied to ferns. The spores are located under the fern leaf. Each spore becomes a heart shaped gametophytes. Some ferns are hetero- or homo-sporophytes. They create male and female or just female ferns.

Alternation of generation can be applied to gymnosperms. The tree is the sporophytes. The gametophyes are located in the cones of the trees. The male cones are only on the tree for 3-4 weeks before completing the reproductive cycle. The female cones can stay on the tree for 3-4 years.

Alternation of generation can be applied to angiosperms.

Flower Review

“A diagram of the parts of flowers” Photo credit to Science & Plants for Schools retrieved from

Ovule contains the embryo sac surrounded by integuments. Three cells are located at the bottom, the center one is the egg and the two that surround it are synergids. The three cells located at the top are antipodals. Two haploid polar nuclei are located in the middle. Ovule is the female gametophyte.

Embryo Sac = Female Gametophyte
Pollen Grain = Male Gametophyte

Double Fertilization is unique to angiospersms. A double fertilization occurs when a female gametophyte (embryo sac) and two male gametophytes (sperm) encounter each other. The sperm make its way down the pollen tube . One sperm produces endosperm, and one produce embryo. The endosperm is a nutritive tissue in seeds to feed the embryo.

Plant reproduction is complex.
There are sexual and asexual reproduction, but there are also apomictic seeds, agamospermy. The agamospermy produce seeds that are clones of themselves. This occurs in dandelions.

Perfect Flowers vs. Stamenate or Pistillate Flowers

Monoecious vs. Dioecious Plants

Androdiecy vs. Gynodiecy
Some individuals produce perfect flowers and some produce only male or female flowers.

Some of these species are obligate outcrossers. These outcrosser needs pollen from another plant and cannot self pollinate
Some of these species are obligate selfers. These selfers can only self pollinate.
A lot are flexible enough for both outcrossing and selfing to happen.

How does mating system influence geographic range size for selfers vs. outcrossers?
Selfers have a bigger geographic range because they can spread even with low densities. They have reproductive assurance.


Ornaments, Not Just for Christmas

When the average person hears the word ornament they think of Christams. The lights, smell of pine trees, with big red and silver globes hung from the branches, but ornaments aren’t just for the holidays. Organisms can possess ornate physical traits that are used for sexual selection. The males organisms of various species don’t have the advantage of having a mistletoe to kiss under, so they use ornamental traits and features to attract mates.

Ornamental features were defined by Darwin as dramatized traits used for the competitive behavior among mate acquisition. These traits often cause a cost to the physical resources of the organism and have no survival benefit. Females are thought of as passive, choosy, and coy while males get the reputation of being competitive and sexually indiscriminate. This theory of the contrast in sexual behaviors, although over simplified, gives a good representation of why male organisms possess these traits to attract females. However, females posses these ornamental traits as well for a whole different reason.

Unlike their male counterparts, females who display ornamental traits will utilize these traits for competing with other females when in comes to ecological resources instead of mate competition. These resources include those for reproductive fitness and materials needed to rear their young. The use of ornamental traits also has an impact on the social structure between females. In this aspect it is hard to differentiate which traits in females or males are due to social selection rather than more widely known and accepted sexual selection.