Bird Evolution PDF

# Bird Evolution ## Class: Aves **What is a bird?** (Have Feathers) - Endothermic, vertebrate - High metabolic rate - Four-chambered heart - Beak with no teeth - Bipedal - Arms modified as wings to reduce weight for flying - Lays eggs with a hard outer shell - Strong, lightweight skeleton - Sist...

# Bird Evolution ## Class: Aves **What is a bird?** (Have Feathers) - Endothermic, vertebrate - High metabolic rate - Four-chambered heart - Beak with no teeth - Bipedal - Arms modified as wings to reduce weight for flying - Lays eggs with a hard outer shell - Strong, lightweight skeleton - Sister to Crocodiles - Diverged in Late Jurassic - ~160 mya - Lay eggs. ## Bird Evolution - Evolved from theropod dinosaurs - Early Feathers Used for insulation, camouflage, and attraction. ### Key Adaptations for Flight - Reduction and fusion of digits - Hollow bones - Fusion of clavicles (furcula) - Feather development - Arms too short - Bodies too heavy - Closed with barbules and hooks - Asymmetrical feathers (flight) - Loss of teeth - Reduction of bony tail (pygostyle) - Modern birds diverged -150 mya # Anatomy of the Feather - **Calamus:** Smooth base of the feather that extends into the follicle. - **Rachis:** Main shaft of the feather - **Barbs and Barbules:** Lateral branches off of the rachis. Barbs contain hooks. - **Vane:** Flat surface on each side of the feather made up of barbs and barbules held together by the hooklets. ## Types of Bird Feathers - **Contour Feathers:** Cover body, protection - **Remiges:** Flight feather on wing - **Retrices:** Flight feather on tail. - **Plumulaceous Feathers:** (lack hooklets) - **Semiplume:** Under contour feathers, sense position of contour feathers. - **Filoplume:** Under contour feathers sense position of contour feathers. - **Bristles:** Stiff rachis and typically lack barbules, Protect eyes and face, sensory. - **Downy:** Under contour feathers, insulation ## Evolution of the Feather - Initially believed to have evolved from scales - Keratin - Evolved for insulation, co-opted for display and later flight (Exaptation) ### Five states of feather development 1. Single filament with a hollow shaft 2. Tuft of filaments with a hollow shaft 3. Filaments fuse to form a solid shaft, barbs stem from shaft 4. Barbules stem from barbs 5. Barbules develop hooklets that interlock adjacent barbs, asymmetrical shape in flight feathers # Feather Growth and Development 1. Formation of dermal papilla 2. Formation of follicle 3. Formation of epidermal ridges - Ridges form into barbs and barbules 4. Open feather - Corneal sheath degenerates ## Feather Function: - Flight - Insulation - Downy feathers - Heat absorption - Nesting material - Mate attraction - Camouflage - Protection from elements ## Plumage Coloration: - **Biochrome pigments:** Naturally occurring chemical compounds that reflect certain wavelengths of light - **Melanins:** Brown, black, beige, gray - **Carotenoids:** Red, yellow, orange - Derived from diet - **Porphyrin:** Bright brown, green, magenta. ## Structural Coloration: - **Constructive Interference:** Microscopic structures within the feather reflect certain wavelengths of light - White, blue, green, red, iridescent feathers ## Molting **Benefits:** - New, bright feathers for breeding - Reduction of parasite load **Costs:** - Energetically Demanding - Susceptible to predation # Adaptations to Flight - **Furcula:** Fused clavicles that compress and rebound during downstroke. - **Keel:** Projection of sternum used in flight muscle attachment - **Synsacrum:** Fusion of caudal and lumbar vertebrae. Absorbs shock when landing. - **Pygostyle:** Fused tail vertebrae that supports and controls tail feathers - **Carpometacarpus:** Fusion of hand and wrist bones for strength. - **Hollow Bones:** Long bones have air pockets and are reinforced with struts. ## Muscles: - **Downstroke** - **Pectoralis:** Muscles contracts, attached to the ventral side of the humerus - **Upstroke** - **Supracoracoideus:** Muscle contracts, attached to the dorsal side of the humerus by tendon ## Theories on Flight - **Wing Assisted Incline Running:** Arms with feathers aided in running up an incline. - **Cursorial Theory:** Elongated limbs with feathers increased leaping ability - **Arboreal Theory:** Elongated limbs and feathers aided in gliding or parachuting from trees. # Feet type - **Anisodactylie:** Three upfront, one back (most songbirds) - **Zygodactylie:** Two upfront, two back (woodpecker) - **Tridactylie:** Three toes (Emu) - **Didactylie:** Two toes (ostrich) # Migration: - More than half of North American birds (650 species) are migratory. - Move from areas with low or decreasing resources to areas with more resources. - Food and nesting territory initiated by changes in day length. Long-distance migrants directed by Earth's magnetic field, visual cues, stars. ## Types of Migrants - **Residents:** Stay in the same location year round. Adequate resources to survive - **Short Distance:** Higher elevations to lower elevations in the winter - **Long Distance:** Typically move from breeding ranges (i.e., Canada) to wintering ground. In central and South America, returning from wintering grounds. Four main flyways. Longer days and more insects in northern latitudes during summer. Larger clutch sizes - # Flocking **Advantages:** - **Foraging:** Finding food - **Protection:** Predator detection, mobbing - **Mating:** Increased selection of mates - **Chick rearing:** Protection from predators - **Aerodynamics:** Less air resistance, warmth -- share body heat **Disadvantages:** - **Visibility:** Attract predators - **Competition:** Competition for food and mates - **Disease:** Higher densities = greater disease transmission # Attracting a Mate - **Song**: Sung performance depicts male quality, territorial defense. - **Displays:** Male performance and ornamentation demonstrate male quality. - **Lek:** Communal display area where males perform for females. - Good-genes hypothesis - Birds of Paradise - Grouse ## Breeding Systems - **Monogamy:** Neither sex has the opportunity to monopolize additional mating partners. Most common mating system in birds. Shared parental care maximizes reproductive success. ~3% of bird species - **Polygamy:** Multiple mating partners - **Polygyny:** Males control or have access to two or more females. ~2% of bird species - **Polyandry,** Females gains access to multiple males. ~21% of bird species. - **Polygynandry:** Several females and several males form a communal breeding unit. Makes parental effort leveled to confidence of paternity ## Songs and Calls - **Calls:** Short, simple vocalizations given by either sex. Distress, flight, warming, feeding, resting. Found in most birds. - **Songs:** Longer and more complex calls used in territorial male birds. (i.e., Hummingbirds, songbirds, parrots) ## Bird Development: - **Altricial:** Young are immobile, lack down, and have closed eyes after hatching. Essential parental care, fast growth. - **Precocial:** Young are mobile, have downy feathers, and open eyes after hatching; minimal parental care (self-feeding) # Perching Birds: - **Perching:** A tendon behind the tibiotarsus allows for the weight of the bird sitting to tighten on the perch. This locks the foot shut. ## Bird Classification - **Ratites:** (Flightless birds) - **Carinates:** (can fly) # Brood Parasitism - The practice of laying eggs in another individual's nest to pass the cost of rearing the offspring off on another individual leaving the offspring to be raised by the foster parents. # Class: Mammalia - Endothermic vertebrate - Amniotic egg - Four-chambered heart - Differentiated teeth - Two sets of teeth - Diphyodont dentition - Two occipital condyles ## Synapomorphies of Mammals - Mammary glands - Hair - Three middle ear bones - Neocortex region of brain - Single lower jaw bone (mandible) ## Evolution History of Mammals - **Based on the number of temporal openings (Fenestra)** - Jaw muscle movement - **Anapsid:** No temporal openings - **Synapsid:** Single Temporal opening - **Diapsids:** Two Temporal openings # Synapsids: - Large temporal fenestra - Differentiated teeth on single dentary bone - Hinge between quadrate and articular # Therapsids - Further differentiation of teeth - Canines and incisors - Larger dentary bone # Cynodonts: - Cusped teeth - Secondary palate - Hinge forms between dentary and squamosal - Quadrate and articular bones migrate to inner ear - Single lower jaw bone (dentary) ## Reptile - 3 bones bottom jaw: - **Mammal** - 1 bone bottom jaw ## Middle ear Reptile - 1 bone: - **Mammals** - 3 bones (middle ear) - **Shifted hinge for force** - Hyenas, Jaguars # Modes of Locomotion - **Plantigrade:** (walking on flat foot) (humans) - **Digitigrade:** (heel off ground) (cats/dogs) (walk on toes) - **Unguliglade:** (Walk on hoofs) (Antelope, horses, pigs) # Lactation vs. Gestation Times - **Gestation:** How long they "look" inside the placenta (period of gestation). - **Marsupials** - Young born in a very immature state - Dependency on yolk sac for nutrition. - Short gestation period - Prolonged lactation period - **Eutherians** - Facilitates nutrient transfer between embryo and mother. - Young born in a well-developed state - Long gestation period. - Short lactation period ## Lactation: - Secretion of milk from mammary glands. - Transmits passive immunity. - Modified sweat glands. - Produces **prolactin:** Stimulates milk production. - Produces **oxytocin:** Stimulates milk delivery. - Milk: Nutritional liquid comprised of fats, proteins, and lactose. Supports the growth of intestinal flora. ## Major Lineages of Mammals - **Monotremes:** - Lack a placenta - Leathery eggs similar to reptiles. - True cloaca. - Body temp. ~32*C - **Marsupials:** - Rudimentary, short-lived placenta. - Short gestation period - External cloaca only - Body temp. ~35*C - **Eutherians (Placentals):** - Placenta - Separate urinary, fecal, and reproductive openings - Body temp. ~38*C ## Differences in the Placenta - **Marsupials:** - Rudimentary connection between yolk sac and maternal tissue - Large yolk sac provides nutrients to developing embryo - Allantois (avascular): Storage of nitrogenous waste - **Eutherians:** - Umbilical cord connects fetus to uterus - Umbilical vein and artery   - Efficient exchange of nutrients, gases, and waste   - Reduced yolk sac   - Allantois connects fetal bladder to yolk sac, which drains into umbilical chord ## Biogeography Of Mammals - **Early Jurassic (~200 mya):** Monotremes and marsupials in southern Pangea. - **Late Jurassic (~180 mya):** Eutheria diverge from marsupials in "South America." - **Early Cretaceous (~135 mya):** Marsupial and monotremes isolated in "Australia" and marsupials are isolated in "South America." - **Early Paleocene (~65 mya):** - Dinosaurs extinct - Mammal radiation - Eutheria wide distribution - Introduced to Australia - Scrotum posterior to penis - Baculum - Sometimes present - Separation of primates - New world/old world lemurs - Eutheria have single reproductive tract - One vagina with a uterus - High metabolic rate - Body temp. ~38*C - Eutheria northern distribution - Large braincase (relative to body size) - Complex neocortex: Higher functions including sensory perception, language, spatial reasoning, motor commands. - Corpus callosum: Connects left and right hemispheres of brain - **Marsupials:** - Limited to Australia and the Americas. - Yolk sac placenta - High metabolic rate - Body temp. ~35*C - Marsupium (pouch) often present - Scrotum anterior to penis - No baculum - Females have a bifurcated reproductive tract. - One vagina and two uteri. - Male penis bifurcated at the tip.   - Small braincase relative to body size   - Minimal neocortex development.   - No corpus callosum. # Primate Evolution - **Ancestral primates:** (arboreal): 65 mya - Binocular vision - Opposable thumb - **Prosimians:** (Lemurs, tarsiers, pottos) - **"Ida":** Ancestral primate (arboreal) 47 mya - Binocular vision - Opposable thumb - Missing link - No claws - Lack a tooth comb - Short limbs - Short face - Talus - corner of leg/foot - **Anthropoids:** (50 mya) - **Old World Monkeys:** - External ears close together - Opposable thumbs - Calloused ischial tuberosities (red butts) - **New World Monkeys:** - Broad Flat nasal septum - Non-opposable thumb - Prehensile tail. ## Homonoids: - **(30 mya) (Apes)** - **Human evolution:** - **Sahelanthropus:** 6.5 million years ago - **Laetoli footprints:** 3.5 million years ago. - **Australopithecus:** 3.24 million years ago.   - **Homo genus:** 2.4 - 1.6 mya - **Homo sapiens:** 200,000 years ago - **Neanderthal:** 50,000 years ago ## Human Evolution - **Brain size:** Jaw size got smaller. - **Standing up:** (First thing) - **Bipedalism:** - **Reduced size difference in sexes** - **Family structure:** ## Origin of Modern Humans - **Out of Africa:** (monogeneus) - All races of humans evolved from an ancestor in Africa. - **Multiregional:** Each race evolved from regional populations of Homo erectus. # (Evolution of Nervous System) ## Nervous Systems - **Nerve Net:** - Cnidarian, Ctenophora. - **Nerve Ring with radial nerves:** - Echinodermata - **Bilateral Nervous Systems:** - Cephalization (ganglia or brain). - **Nerve cord:** Area where a lot of neuron cell bodies are piled together. - **Bilateral Nervous System:** Ganglia and two or more longitudinal nerve cords - Platyhelminthes, some mollusca - **Ganglia (brain) and ventral nerve cord:** - Annelida, Arthropoda, some Mollusca - **Brain and dorsal nerve cord:** - Chordata - (Central Nervous System) - **CNS:** Brain, Spinal chord - **PNS:** Everything else - (Peripheral Nervous System) ## Overview of a Nervous System - **Sensory Input:** Conduction of signals from sensory receptors. - **Integration:** Environmental information is interpreted. - **Motor Output:** Conduction of signals to effector cells. - **Neurons:** - **Cell Body:** Nucleus and organelles. - **Dendrites:** Short and branched, toward cell body. - **Axons:** Long and unbranched, away from cell body. - (makes myelin sheath) - **Myelin Sheath:** Insulating layer - **Node of Ranvier:** Gaps between Schwann cells - **Synaptic Terminals:** Neuron ending. ## Cluster of Neurons - **Ganglion:** Cluster of nerve cell bodies in the PNS - **Nuclei:** Cluster of cells in the brain. - **Glia:** (glue) Supporting Cells - **Astrocytes:** Structural Support, creates tight junctions, and form the blood-brain barrier - **Radial Glia:** Forms tracks for new neurons formed in the neural tube - **Oligodendrocytes:** Form myelin sheath in the brain   - **Schwann Cells:** Form myelin sheath in the PNS. ## Reflex: - Sensory neuron to a motor neuron (built in safety) # Neural Signals - **Membrane Potential:** The difference between the charges. - **Sodium-Potassium pump:** What makes those charges - **A neuron doing nothing has a negative charge inside and a positive charge outside** - **Threshold Potential:** Minimum requirement to set off an action potential ## Resting State - Both sodium and potassium activation gates are closed - Interior of the cell is negative ## Depolarization State: - Sodium activation gates are opened on some channels - Interior of the cell becomes more positive ## Action Potential: - When neurons fire (call or nothing, they happen or they don't) - **Rising Phase:** - Most sodium activation gates are opened - Potassium activation gates are still closed - **Falling Phase:** - Inactivation gates on sodium channels are closing - Activation gates on potassium channels are opened - Interior of the cell becomes more negative - **Undershoot:** - Both gates to sodium channels are closed - Potassium channels are closing - Membrane returns to its resting state - **Propagation of the Action Potential** - Localized event - First action potential's depolarization sets off the second action potential   - Travels in one direction to refractory period. Not ready to fire. ## Salatory Conduction - Action potential jumps from node to node. - Speeds up the signal from 5 msec to 150 msec. ## Communication Between Synapses - **Electrical:** Gap junctions allow for direct transfer of action potential, used during escape responses. - **Chemical:** Uses neurotransmitters. - (All 5) Action potential triggers an influx of calcium. - Synaptic vesicle fuses with presynaptic membrane - Neurotransmitter released into a synaptic cleft ​ - Neurotransmitter bind to receptors and open ion channels on postsynaptic membrane which set off a new action potential - Neurotransmitter are degraded by enzymes or removed by a synaptic terminal ## Neurotransmitters ## Postsynaptic Potentials - **Subthreshold:** Doesn't reach threshold - **EPSP:** Excitatory - **IPSP:** Inhibitory ## (Time) - **Temporal Summation:** The signals do not reach threshold level but occur close enough to set off action potential - **Spatial Summation:** Two signals are set off at the same time setting off an action potential - **Spatial Summation with an inhibitor:** Doesn't reach threshold # (CNS) ## Vertebrate Nervous System - **Ventricles:** (4) - **Cerebrospinal fluid** - **White matter:** Made up of axons - **Gray matter:** Made up of dendrites. ## Peripheral Nervous System - **Autonomic:** Regulates the internal environment (usually involuntary). - **Sympathetic:** Fight or flight response. - **Parasympathetic:** Rest or digest response. - **Enteric:** Occuring in the intestines. - **Somatic:** (Voluntary muscle) - Regulates the external environment (usually involuntary). ## Brain - **Medulla Oblongata and Pons:** Controls breathing, heart rate, digestion - **Cerebellum:** Coordination of movement and balance - **Midbrain:** The midbrain receives, integrates, and projects sensory information to the forebrain - **Hypothalamus:** Produces hormones and regulates body temperature, hunger, thirst, sexual response, circadian rhythms. - **Thalamus:** Conducts information to specific areas of cerebrum. - **Epithalamus:** Includes the pineal gland and the choroid plexus. ## The Telencephalon - **Cerebrum and Corpus Callosum:** With a cortex and corpus callosum; higher thinking. - **Limbic System:** Regulates emotions. Association with different situations is done mostly in the pre-frontal lobe. - **Memory:** - **Short Term:** Done in the frontal lobe. - **Long Term:** Frontal lobes interact with the hippocampus and the amygdala to consolidate. ## Sensory Receptors - **Mechanoreceptors:** (Touch) - **Pain Receptors:** Tell you something is wrong. - **Tonic:** Always there (like pain). - **Phasic:** Something that you can phase out. Can ignore them after a while. - **Thermoreceptors:** (Temperature) - **Tonic or Phasic:** - **Chemoreceptors:** (Chemicals) - (Smelling)-- Tonic - (Because pain can kill you!) --Phasic - **Electromagnetic Receptors:** (Vision) ## Evolution of the Eye - Complex eyes have developed many times. - Have **opsins** (proteins) in common and Pax6 genes in common. ## Photoreceptors: - **Ocelli:** Eye cups (light detection) - During the Cambrian explosion 540 mya. - **Compound Eyes:** Made up of ommatidia that helps detect movement. # Know Picture and Labels from Slides: **Camera-Type Eyes** (Hagfish, Lamprey, Jawed Vertebrates) - **Eye Parts** - **Sclera:** (white) - **Cornea:** (clear) - **Choroid:** (pigmented) - **Iris:** (color of eye) - **Retina** - **Rods:** - **Cones:** - **Pupil:** - **Fovea:** (focal point) - **Blind spot** - **Lens:** (Bending light to a focal point) - **Scars of Evolution:** - **Inside out Retina:** Forcing light to pass through the cell bodies and nerves before reaching the retina - **Blood vessels across the retina:** Cause a shadow - **Nerve fibers that exist:** Causing a blind spot. ## Focusing - **Near Vision:** - Ciliary muscle contracted - Lens becomes more spherical - **Distance Vision:** - Ciliary muscle relaxed - Lens becomes flatter. - **Myopia:** Nearsighted (eye-ball too long; focal point in front of fovea) - **Hyperopia:** Far-sighted (eye-ball too short; focal point behind fovea) - **Astigmatism:** Blurred vision (misshapen lens or cornea) # Hearing and Equilibrium - **Outer Ear:** - **Pinna:** (outer ear to amplify sound) and the auditory canal. - **Tympanic membrane** - **Middle Ear:** - **Malleus:** (hammering sound), incus, stapes. - **Oval window:** - **Inner Ear:** Cochlea with the organ of Corti - With a basilar membrane and hair cells - **Eustachian Tube:** (Inner ear to throat) - Balance ear pressure (drain) ## Sound: - **Volume:** Amplitude of sound wave. Vibrates fluid in the ear and bend hair cells which generates more action potentials. - **Pitch:** Frequency of sound wave ## Equilibrium - **Utricle and Saccule:** - **Semicircular canals** - Used to detect body position and movement - **Lateral Line system:** - Similar to inner ear - Detects movement of current, moving objects - **Statocysts:** - **Equilibrium** - Contains statohiths. ## Sound Systems in Invertebrates: - **Chemoreception:** - **Tastebuds:** - Sweet (tip), Salty (behind), Sour (sides), Bitter (back of tongue) - **Body hairs that vibrates:** - Mosquitos. - Tympanic membrane - Crickets - **Olfactory Receptor Cells:** - Upper portion of nasal cavity. ## The Cost of Locomotion - Locomotion must overcome two forces: **gravity** and **friction**. - **Swimming:** Is more efficient than running (winner must overcome gravity) - **Larger animals:** Travel more efficiently than smaller animals. - **Flight:** Is the most costly (per minute) ## Skeletal Structures - **Hydrostatic Skeleton:** (Cnidaria, Ctenophora, Platyhelminthes, Nematoda, Annelida.) - **Exoskeletons:** (Mollusca, Arthropoda) - **Endoskeletons:** (Chordata) ## Cooperation of Muscles and Skeletons: - Muscles always contract. - Muscles attached in antagonistic pairs. # Know Picture and Labels from Slides - **Know Picture and Labs** (on MCAT) - **Skeletal Muscles: ** Muscles made up of muscle fibers: - Fibers are made up of myofibrils: - Myofibrils are made up of myofilaments - Thin (actin) - Thick (myosin) - **Know Pictures and Labels:** - **Sliding filament model:** - **Sarcomere:** Basic functioning unit. - **Z lines:** (border of sacromeres) - **H Zone:** (center of sacromere) - **I Band:** (only thin filaments) - **A Band:** (length of thick filaments) - **During Contraction:** Thin and thick filaments slide past each other. - **I band and H zone:** Decreases in size. - **Caused by myosin head:** Creating a cross-bridge with action fiber, then moves by using ATP - **Muscle Control:** - **Tropomyosin:** Blocks myosin binding sites - **Calcium ions:** Allow cross-bridges to form. - **Muscle Fibers:** - **Fast Muscle Fibers:** Rapid, powerful contractions. Flight muscle - **Slow Muscle Fibers:** Sustained, long contractions. Abductor muscles - **Invertebrate Muscles:** - Muscles made up of muscle fibers. - Fibers are made up of myofibrils - Myofibrils are made up of myofilaments - Thin (actin) - Thick (myosin) - **Know Pictures and Labels:** - **Sliding filament model:** - **Sarcomere:** Basic functioning unit. - **Z lines:** Border of sarcomeres - **H Zone:** Center of sacromere - **I Band:** Only thin filaments - **A Band:** Length of thick filaments - **During Contraction:** Thin and thick filaments slide past each other. - **I band and H zone:** Decreases in size. - **Caused by myosin head:** Creating a cross-bridge with action fiber, then moves by using ATP. - **Muscle Control:** - **Tropomyosin:** Blocks myosin binding sites. - **Calcium ions:** Allow cross-bridges to form. - **Muscle Fibers:** - **Fast Muscle Fibers:** Rapid, powerful contractions. - Flight muscle. - **Slow Muscle Fibers:** Sustained, long contractions. - Abductor muscles. - **Invertebrate Muscles:**