Loading in 2 Seconds...
Loading in 2 Seconds...
Exam 4 will cover new material through end of Animal Behavior Unit (will complete lecture material for exam on Wednesday). Adaptive function of stereotypical, “innate” behavior
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Exam 4 will cover new material through end of Animal Behavior Unit
(will complete lecture material for exam on Wednesday)
FAP’s, triggered by simple cues do not require extensive time otherwise required for neural processing or integrating wide variety of inputs
Simplecue and relatively simple, stereotypical behavior patterns are effective evolutionary solutions to many situations in the lives of animals, including humans.
Ultimate cause may be that for certain behaviors, automatic and experience-independent modes of expression may have maximized fitness to the point that genes for variant behavior were lost.
Smiling appears spontaneously in human infants at about four weeks. The innate nature of this motor program is illustrated by the smile of this eleven week old blind girl, whose eyes are fixated on source of mother’s voice, a complex behavior that is also innate. Smiling helps cement a strong emotional attachment between parent and child
Hybridization experiment with two species lovebirds demonstrates 1) phenotypic differences in behavior are based on different genotypes, and 2) the behavior can be modified by experience
Molecular genetics research reveals specific genes that influence behavior
Most elements of male courtship behavior are controlled by a single gene
sex-determining pre-mRNAs are spliced in a specific way in females and another way in males
Male sxl and tra mRNAs have stop codons that terminate translation
female sxl and tra mRNAs make proteins that control splicing in the expression of genes in the female-specific hierarchy
the default splicing of dsx mRNAs controls male anatomy
the default splicing of fru mRNAs causes formation of nervous system that expresses male courtship behavior
sex-lethal (sxl) is at the top of a gene hierarchy; it is expressed in fly embryos with two x chromosomes (flies therefore destined to be females).
Japanese macaque that has learned to wash sand off of food before eating
Solomon & Berg 1999
After repeated safe encounters with vans transporting humans on photo safari, many animals, including giraffes, zebras, lions, and elephants, in the Serengeti learn to ignore them. Elephants typically ignore the vans unless the driver provokes them by moving too close. In that event the elephant may challenge and even charge the van
Imprinted goslings following Mom
Ducklings will imprint on the first object they see, eg black box, white sphere
Lorenz being followed by imprinted goslings
Process of imprinting is genetically determined; but bird learns to respond to a particular animal or object
The ability or tendency to respond to first object seen after hatching is “innate”
Imprinting, critical periods, now known to occur at various times in the life of animals, not just in very early stages
Imprinting was initially understood as a learning phenomenon of very young animals (e.g., Lorenz’ geese critical period was first two days of life)
Current understanding is that similar learning processes occur in older animals, and involves a variety of functions
Aspects of imprinting in young falcons
Sonograms of songs of white-crowned sparrows reared under three conditions
Males that heard tapes of conspecific songs before day 50 (a) learned to sing normally, months later. Males raised in soundproof chambers (b) learned only to sing primitive template of song. Males deafened after hearing tapes of conspecific song, but before beginning to practice, did not even learn the primitive template.
Hypothalamic-Pituitary-Gonadal Axis of Birds is Similar to that of Other Vertebrates
Environmental cues, including photoperiod, song
blood streamaccessory sex organs, secondary sex characters, including behaviors
Domestic Chicken, derived from the Jungle Fowl (Gallus gallus) [Galliformes]
Endocrine control of morphological and behavioral components of singing in male canaries
In young zebra finches, male and female song nuclei are similar; females’ nuclei undergo apoptosis, while males continue to grow
(Source: Kirn and DeVoogd 1989)
High Vocal Center
No. neurons in HVc (x104)
Age (days after hatching)
Changes in the song system of young zebra finches. The number of nerve cells in the female’s HVc, a component of the song system, declines rapidly as the males increases
Hormones and Sexual Dimorphism in Behavior and Neural Circuitry
HVc affects song discrimintation by females. The HVc region of the female canary’s song system helps her discriminate between the song of male canaries and that of other species. After destruction of the female’s HVc, she will perform copulatory displays to tapes of white-crowned sparrows. (After Alcock 1998, Brenowitz 1991)
Life, lineages, evolved in 24-hour cycles of light and dark
Across kingdoms, lineages have endogenous circadian rhythms of activity -- eating, sleeping, motor patterns (e.g. treadmill), metabolic function…
“Biological clocks”, the proximate mechanisms that drive circadian rhythms, are fundamentally important organizers of animal behavior
The period (length of time of period) of circadian rhythm is entrained (set) by an environmental cue; light-dark cycle; organisms deprived of the environmental cue will continue rhythmic behavior in a free-running manner with periods that are about, but not exactly 24 hours (“circadian” = “about a day”)
Period = one cycle length Phase= point on the cycle
Entrainment= setting, resetting of clock, via environmental cue; drives phase advances or phase delays as well as periodicity
Circadian rhythms occur throughout kingdom Animalia; Also occur in protistans, plants, fungi
Within animalia, among lineages, there are diversity in clocks, ie, evolution of diversity in “location, tissue, and presumably cell molecular mechanisms
In mammals, “master circadian clock” is located in the brain, in two nuclei dorsal to the optic chiasm; the suprachiamatic nuclei
Genetic underpinnings of circadian rhythms. Many alleles of the period gene of Drosophila fruit flies exist. On the left is shown the strand of DNA that constitutes the period gene. Researchers know precisely where different mutations have occurred in this stretch of DNA. Each mutant allele has a characteristic effect on the activity patterns of fruit flies, shown on the right (dark bars represent time when the flies are active). The normal pattern of nonmutant (wild-type) flies appears at the bottom of the diagram [Baylies et al, in Alcock 1998]
Manipulation experiment demonstrates role of period gene in Drosophila Wildtype DNA from fruit flies can be take up in plasmids, some of which will then carry the per+ allele. The plasmids can then be collected and microinjected into the embryos of fruit flies with the pero “restoring” normal activity
The dimer is translocated to the nucleus where it inhibits further transcription of the per and tim genes
per and tim dimerize in the cytoplasm
Transcription and translation of per and tim show circadian rhythms
Rates of transcription, translation, dimerization, may be cell-molecular components of the biological clock
Migration Feat: Monarch butterflies of eastern North America in a remote fir forest in Mexico; the migration is over 3000 kilometers and takes from two to five generations to complete
dots represent pecks for food
bird is trained to seek food in the south
bird with 6-hr phase advanced rhythm now seeks food in east
A pigeon placed in a circular cage from which can see the sky (not the horizon) can be trained to seek food in one direction, even when its cage is rotated between trials
Pigeon is placed on altered light-dark cycle and its circadian rhythm is phase-advanced by 6 hrs. Bird is then returned to the training cage under natural sky
Starlings and certain other birds have an “internal clock” they use to compensate for the sun’s apparent movement through the sky
Magnetite, a magnetized iron ore, has been found in the brains of some birds, but the sensory receptors birds use to detect magnetic fields have yet to be identifieid
Orientation of homing pigeons is influenced by changes in magnetic field. Dots show angles at which birds flew off. Direction of home is straight up. Birds tested for two magnetic directions, neither of which affect birds on sunny days, but both do on overcast days, suggesting a back-up system.
Starling Migration Displacement experiments indicate that inexperienced starlings migrate by orientation (and is largely an “innate” behavior) while older birds that have migrated previously use true navigation (and modify their migration behavior through experience.