VSCI1100: BEHAVIOR, GENETICS, EVOLUTION & DOMESTICATION

What are the three core learning objectives for Module 2 of the Ethology course?

1. Understand the roles of genetic inheritance, heritability, and epigenetics.
   2. Analyze the "domestication syndrome" across species.
   3. Apply evolutionary adaptation concepts to explain retained ancestral drives (e.g., rooting in pigs).

What is the "Key Concept" regarding animals performing complex, goal-directed behaviors like nest building or migration without prior learning?

Modern science confirms that genes (DNA) contain chemical instructions for behavior development, and evolution modifies gene frequency across generations.

How did Charles Darwin describe behaviors like bird migration that are transferred from parents without learning?

He referred to them as "instinctive" behaviors and proposed they are the "raw material" for evolution.

Who is known as the "father of genetics" for his pioneering experiments on inheritance using pea plants?

Gregor Mendel, known for Mendel's Laws.

What are Mendel's three laws of inheritance?

1. Law of Dominance: One trait masks the expression of another.
   2. Law of Segregation: Two alleles of a gene separate during gamete formation.
   3. Law of Independent Assortment: Alleles of different genes assort independently.

In Dilger’s 1962 Lovebird experiment, how did Fischer's lovebirds and Peach-faced lovebirds differ in nest-building behavior?

Fischer's lovebirds carry material one piece at a time in the beak, while Peach-faced lovebirds tuck strips into their rump feathers.

What was the result of Dilger’s (1962) hybrid lovebird experiment?

The hybrids showed dysfunctional intermediate behavior (attempting to tuck but failing to release), providing evidence for the genetic inheritance of behavior through non-dominant alleles.

In Manning's (1961) fruit fly experiment, how did mating time change after 25 generations of selection?

Mating time between the "fastest" and "slowest" lines differed by approximately 30 minutes.

What did Hirsch's (1967) experiment on geotaxis in Drosophila demonstrate?

Rapid divergence between lines selected for positive vs. negative geotaxis in just a few generations, proving behavior is under genetic influence.

In Lynch's (1980) mouse experiment, what was the difference in nest-building behavior after 15 generations of selection?

One line collected ~50 g of cotton for nests compared to only 5–10 g in the other line.

What did Kjaer & Sorensen (1997) confirm regarding feather-pecking in laying hens?

That the behavior has a genetic basis, as genetic selection against it successfully reduced the behavior across generations.

Why is genetic control of behavior considered "universal"?

Because the DNA/RNA toolkit and control mechanisms are largely the same from yeast to mammals.

What is the definition of Heritability (( h^2 ))?

The proportion of phenotypic variation in a population that is attributable to genetic variation.

True or False: High heritability means a trait is "genetically determined."

False. It means genes account for a larger share of variation in that specific environment; it is not a measure of fixedness.

Why is behavior considered a quantitative trait?

Because it is typically polygenic, meaning multiple genes interact to produce the phenotypic outcome.

In the maze-learning experiments by Tryon (1940), how were "bright" and "dull" rat lines created?

Through artificial selection based on maze-learning ability across several generations.

What did Cooper & Zubek (1958) discover when they raised Tryon's "bright" and "dull" rats in enriched or impoverished environments?

1. Standard environment: "Dull" rats made more errors.
   2. Impoverished environment: Both lines performed equally poorly.
   3. Enriched environment: Both lines performed equally well.

What is the "Correct View" regarding Gene-Environment Interaction?

Genes create predispositions, not fixed outcomes; the environment determines which genetic potential is expressed.

What is Genetic Determinism?

The mistaken belief that if a behavior has a genetic basis, it is inflexible and determined from fertilization.

According to Per Jensen (2009), what do genes supply to the organism regarding behavior?

Genes supply the structural and physiological substrate (limbs, nerves, etc.), but behavior develops in interaction with the environment.

How does the environment affect the genetic predisposition for feather-pecking in hens?

A genetic predisposition to peck only results in feather-pecking if the environment lacks appropriate pecking stimuli; in a stimulus-rich environment, it may never develop.

In Scott & Fuller’s (1965) dog study, what was found regarding the inheritance of struggling when restrained?

It is controlled by one allele, with the Basenji trait being dominant over the Cocker Spaniel trait.

In Scott & Fuller’s (1965) dog study, how many genes control the tendency to bark?

It is controlled by two genes, with Basenjis having a high stimulus threshold (rarely barking).

What is the effect of the 'dunce' mutation in fruit flies?

A single gene mutation on the X chromosome prevents the fly from learning to avoid odors associated with electric shocks by affecting cAMP phosphodiesterase.

How do mutations in the nematode C. elegans affect behavior?

One mutation alters myosin filaments leading to uncoordinated movement, while another affects chemoreceptor structure leading to altered chemical receptivity.

What is the indirect pathway through which a gene affects behavior?

1. Protein synthesis instructions
   2. Regulation of metabolism/hormones/neurotransmitters
   3. Impact on neural development/receptor sensitivity
   4. Shaping of neural architecture
   5. Emergence of observed behavior.

When behavior changes gradually across generations of selection, what type of genetic control is indicated?

Polygenic control (multiple genes acting together).

What is the first step in localizing genes tied to behavior?

Locating the position on the chromosomes that is related to the expression of the behavior.

What is Linkage in behavior genetics?

When behavior is inherited in close correlation to another trait because their genes are located close to each other on the chromosome.

What is the difference between QTL analysis and GWAS?

Quantitative Trait Loci (QTL) and Genome-Wide Association Studies (GWAS) both map chromosomal regions correlated with traits, but GWAS scans the entire genome for marker-trait correlations.

What behavioral change was observed in Knockout mice lacking the oxytocin gene?

They showed reduced aggressive behavior and milk ejection failure.

What is CRISPR-Cas9?

A novel, low-cost gene-editing tool derived from bacterial virus defense systems used to silence or modify DNA sequences.

What is the definition of Epigenetics?

Chemical modifications of DNA (like methylation) that affect gene expression WITHOUT altering the DNA sequence itself.

What are the two major mechanisms of epigenetics?

1. DNA Methylation: Addition of a methyl group (( \ce{CH3} )) typically silences genes.
   2. Histone Modification: Chemical modification of proteins that package DNA, activating or silencing expression.

In Kappeler & Meaney’s (2010) study, what happened to rat offspring raised with high-quality maternal care?

They showed greater stress resilience as adults and became more attentive mothers themselves due to epigenetic modifications of the glucocorticoid receptor gene.

What did Jensen (2015) discover about stressed chickens and their offspring?

Stress responses and altered learning abilities were transferred to offspring even if they didn't experience the stress, a neo-Lamarckian mechanism.

How does epigenetics relate to the red junglefowl and modern egg-layers?

DNA methylation and gene expression in the brain differ substantially between the two, suggesting epigenetics accelerated domestication faster than mutation alone.

What are Darwin’s Three Principles of evolution?

1. Variation: Traits must vary between individuals.
   2. Genetic Inheritance: Variation must have a genetic origin.
   3. Natural Selection: Variants must cause different reproductive abilities.

What are the three types of selection shown in population curves?

1. Stabilizing selection: Favors intermediate variants (e.g., robin egg clutch size).
   2. Directional selection: Favors one extreme (e.g., peppered moths).
   3. Diversifying/Disruptive selection: Favors both extremes (e.g., gray/Himalayan rabbits).

How can we study the evolution of behavior in the past given limited fossil evidence?

Through Behavioral Archaeology (e.g., Archaeopteryx skeleton suggesting flight evolution) and mapping behavior onto phylogenetic trees.

What did Prum (1990) discover by mapping Manakin courtship behaviors onto a phylogenetic tree?

Evolution generally added elements over time (repertoire expansion), though some lineages lost patterns.

How did the Greenish Warbler provide evidence for behavioral evolution?

It is a "ring species" where geographic separation and female mate preference drove speciation and the differentiation of song traits.

What is Ritualization?

The evolutionary process where a behavior originally serving one function is modified into a signal by becoming exaggerated and losing its original function.

How did Peacock courtship evolve via ritualization?

It derived from ancestral "tidbitting" (pecking at food while calling). The behavior became unrelated to food and shifted to the colorful tail spread.

Does behavior evolve "for the good of the species"?

No. This is a misconception. Evolution works on variation between individuals, and behavior is selected based on individual fitness (reproductive success).

In the context of behavior, what is Fitness?

Reproductive success; the ultimate measure of the benefits of an individual's behavior.

What is "Optimal Behavior" in evolutionary theory?

The behavior that maximizes the difference between fitness benefits (mates, food) and fitness costs (energy, risk).

What are the three factors that determine an optimal decision in Optimal Foraging Theory?

1. Depletion of current patch.
   2. Profitability of alternative patches.
   3. Travel time to a new patch.

What is the Marginal Value Theorem?

The principle that an animal should leave a food patch when its net energy intake per unit time is maximized.

What is an Evolutionarily Stable Strategy (ESS)?

A strategy that, when adopted by most of a population, cannot be invaded by an alternative strategy because it is self-stabilizing.

What is the Proto-domestication hypothesis by Budyansky (1992)?

The idea that animals partially "chose" domestication to exploit human settlements for fitness benefits before active human breeding programs began.

Compare the Standard (Cultural) Model and Biological Model of domestication regarding timing.

Standard Model: Began ~10,000 years BP with sedentary man.
Biological Model: DNA evidence suggests it began 50,000–100,000 years BP in some species.

Which two groups of animals show a strong taxonomic bias in domestication?

1. Ungulate mammals (cattle, sheep, horses).
   2. Gallinaceous birds (chickens, turkeys).

According to Price (1997), what are four key behavioral traits that facilitate domestication?

1. Gregariousness (social living).
   2. Omnivorous/herbivorous diet.
   3. Weak mate bonds.
   4. Non-territoriality (or flexible territory).

What is the difference between the First Wave and Second Wave of domestication?

First Wave: (~10k+ years BP) Biologically "pre-adapted" species (dogs, cattle).
Second Wave: (Recent centuries) Completely human-controlled (mink, lab rats) that may lack classic facilitating traits.

What are the typical morphological changes seen in the "Domestication Syndrome"?

Altered color (white/spotted), changed shape (compressed skulls, shorter legs), and reduced seasonality in reproduction.

True or False: Domestication has added many new behaviors to the behavioral repertoire of domestic species.

False. Research (Price, 1997) found no new behaviors added; differences are subtle and involve changes in frequency or threshold.

What three behavior types are part of the "Domestication Syndrome"?

1. Modified stimulus thresholds (e.g., barking).
   2. Reduced fearfulness toward humans.
   3. Increased social tolerance toward conspecifics.

What is the "Fundamental Principle" of retained ancestral drives?

Behavior is controlled by genetic mechanisms shaped over thousands of wild generations and is only slightly altered by domestication.

Why does failure to provide nesting material cause welfare problems in domestic pigs?

Because they retain the ancestral drive for pre-farrowing nest building; lacking a substrate leads to stereotypies and aggression.

Which ancestral behaviors are retained by laying hens even in battery cages?

Perching at height for safety, dust-bathing, and pre-laying nesting behavior.

What are three unique socio-cognitive adaptations dogs have evolved for cooperation with humans?

1. Sensitivity to human ostensive cues (pointing, gaze).
   2. Word and command comprehension.
   3. Active solicitation of human help (unlike wolves).

Human-directed social behavior in dogs is linked to genes associated with which human disorders?

Autism Spectrum Disorder (ASD) and ADHD.

What did Konermann et al. (2015) emphasize about CRISPR-Cas9?

It enables single-lab investigations of gene-behavior links due to being a novel, low-cost tool.

What was the "Intermediate stage" of peacock courtship evolution according to Schenkel (1956)?

Movements became exaggerated, similar to those seen in modern pheasants.

Define Geotaxis.

The movement of an organism in response to the force of gravity.

What is the difference between Genetic Predisposition and Heritability in the "Key Distinction" table?

Predisposition means genes bias probability while the environment shapes the outcome; Heritability is the proportion of population variation explained by genes.

What did Jensen (2016) note about wolves compared to dogs in problem-solving?

Wolves do not show the active solicitation of human help that dogs do when facing a challenge.

How does social tolerance differ between domestic pigs and wild boars?

Domestic pigs tolerate higher densities than wild boars, which is an adaptive advantage in group-housing settings.

What is the "Standard Environment" in the rat maze studies?

The baseline laboratory environment used to compare the performance of "bright" and "dull" rat lines.