Avian Reproductive Biology Quiz
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Questions and Answers

What is the primary function of the ovum in birds after fertilization?

  • To develop into an embryo (correct)
  • To release hormones
  • To produce yolk layers
  • To provide energy for the female

    • In which part of the female bird's anatomy does sperm from multiple males compete to fertilize the ovum?

  • Cloaca
  • Ovary
  • Storage tubules (correct)
  • Seminal vesicles

    • How do bird testes respond during the breeding season?

  • Increase in size by 500% (correct)
  • Remain constant in size
  • Occupy an external sac
  • Decrease in size by 50%

    • What is the primary method of copulation in most birds without a penis?

    <p>Intromission via a cloacal kiss</p> Signup and view all the answers

    What distinguishes the composition of yolk in bird eggs?

    <p>Contains both yellow and white yolk</p> Signup and view all the answers

    What role does the cloaca play in birds?

    <p>Facilitates both excretory and reproductive functions</p> Signup and view all the answers

    What is a unique feature of certain waterfowl in relation to their reproductive anatomy?

    <p>They possess elaborate spiral penises</p> Signup and view all the answers

    What predominantly influences the timing of sperm formation in birds?

    <p>Body temperature stabilization at night</p> Signup and view all the answers

    What is the primary purpose of bowers created by bowerbirds?

    <p>To display social status and health to potential mates</p> Signup and view all the answers

    In the Hotshot Model of lek evolution, which males do younger males tend to cluster around?

    <p>Experienced, attractive, or dominant males</p> Signup and view all the answers

    Which statement correctly defines monogamy in bird species?

    <p>A pair of birds share parental care</p> Signup and view all the answers

    What is a significant benefit of cooperative breeding for helper birds?

    <p>Gain direct or indirect fitness benefits</p> Signup and view all the answers

    Which breeding system is characterized by the female defending resources to attract multiple males?

    <p>Polyandry</p> Signup and view all the answers

    What behavioral trait does brood parasitism typically exemplify?

    <p>Cheating parental care costs</p> Signup and view all the answers

    In the context of lek behavior, what is the Female Preference Model?

    <p>Females prefer to visit large clusters of males</p> Signup and view all the answers

    Which type of bower is characterized by sticks built around a central pole?

    <p>Maypole bower</p> Signup and view all the answers

    What is a common characteristic of obligate brood parasites?

    <p>They rely solely on other species for rearing their young</p> Signup and view all the answers

    What role do older male Purple Martins typically play in extra-pair copulations?

    <p>They concentrate on copulating with mates of naive younger males</p> Signup and view all the answers

    What is one of the ecological factors that might promote cooperative breeding?

    <p>Limited access to quality habitats</p> Signup and view all the answers

    How does kin selection explain altruistic behavior in cooperative breeding?

    <p>Helpers gain indirect fitness by supporting closely related individuals</p> Signup and view all the answers

    What percentage of offspring in some species, like Tree Swallows, is commonly fathered by males outside the mated pair?

    <p>Up to 50%</p> Signup and view all the answers

    Which evolutionary model explains males gathering based on where they are likely to encounter females?

    <p>Hot Spot Model</p> Signup and view all the answers

    What role does albumen play in avian eggs?

    <p>Adds shock absorption and insulation to the egg</p> Signup and view all the answers

    Which of the following best describes the relationship between egg yolk percentages and chick maturity at hatching?

    <p>Higher yolk percentages correlate with more mature chicks</p> Signup and view all the answers

    What is the primary purpose of the eggshell in avian biology?

    <p>Provide structural support and protection</p> Signup and view all the answers

    What does 'lek' refer to in avian mating behavior?

    <p>A communal display ground for males</p> Signup and view all the answers

    Which evolutionary hypothesis suggests that elaborate sexual traits provide material benefits to females?

    <p>Direct benefits hypothesis</p> Signup and view all the answers

    How do elevated male displays contribute to reproductive success?

    <p>They attract females by showcasing health and vitality</p> Signup and view all the answers

    What mechanism allows embryos to perform gas exchange within the egg?

    <p>Microscopic pores in the eggshell</p> Signup and view all the answers

    Which bird species is known for exhibiting the longest tail among males that increases mating success?

    <p>Long-tailed Widowbird</p> Signup and view all the answers

    What is the main evolutionary advantage of sexual dimorphism in birds?

    <p>Enhancing reproductive success through mate selection</p> Signup and view all the answers

    Which structure surrounds the developing embryo and provides a protective environment?

    <p>Amnion</p> Signup and view all the answers

    In terms of reproductive success, what can be inferred from the male Bokolink's display time being reduced?

    <p>Their fitness may be perceived as low</p> Signup and view all the answers

    Why might males of cliff-nesting species develop more pointed eggs?

    <p>To prevent rolling off the nesting site</p> Signup and view all the answers

    What is indicated by brighter males in House Finch populations?

    <p>Increased reproductive success and fitness</p> Signup and view all the answers

    In avian development, where does fertilization typically occur during the egg assembly process?

    <p>In the infundibulum</p> Signup and view all the answers

    What is the structure that encases the yolk in a bird's egg?

    <p>Vitellin membrane</p> Signup and view all the answers

    How do bird testes differ from those of most mammals?

    <p>They maintain a constant temperature.</p> Signup and view all the answers

    What is the primary method birds use during copulation when lacking a penis?

    <p>Cloacal contact</p> Signup and view all the answers

    What is the primary function of the seminal vesicles in male birds?

    <p>Storage of sperm</p> Signup and view all the answers

    Which two bird clades are known to possess a penis?

    <p>Paleognathae and Galloanseridae</p> Signup and view all the answers

    What is unique about the yolk composition in a bird's egg?

    <p>There are layers of both yellow and white yolk.</p> Signup and view all the answers

    What is the role of the central latebra in the yolk?

    <p>Contains fluid composed of vitellin</p> Signup and view all the answers

    What is the primary reason that the size of bird testes can increase during the breeding season?

    <p>To produce more sperm</p> Signup and view all the answers

    Which statement about the development of a mature ovum is correct?

    <p>It involves simultaneous maturation and yolk formation.</p> Signup and view all the answers

    What is the main purpose of the albumen in bird eggs?

    <p>To serve as a shock absorber and insulation for the embryo</p> Signup and view all the answers

    Which factor primarily impacts the structural integrity of avian eggshells?

    <p>Thickness and composition of the calcium carbonate</p> Signup and view all the answers

    In what way do eggs differ across species in relation to chick maturity at hatching?

    <p>Higher yolk percentages correlate with more helpless chicks</p> Signup and view all the answers

    What is the significance of sexual selection in avian species?

    <p>It results in differential reproductive success based on mating success</p> Signup and view all the answers

    What role does mate choice play in sexual selection among birds?

    <p>It encourages males to exhibit elaborate traits that attract females</p> Signup and view all the answers

    What is a characteristic feature of leks in avian mating behavior?

    <p>Leks are communal display grounds with high competition for mates</p> Signup and view all the answers

    What do elaborate sexual ornaments in males often indicate according to the honest advertising concept?

    <p>The male's health and genetic fitness</p> Signup and view all the answers

    Which hypothesis regarding sexual selection suggests that females prefer males with exaggerated traits even when it confers no direct survival benefit?

    <p>Runaway selection hypothesis</p> Signup and view all the answers

    Which of these is NOT a function of the extraembryonic membranes in avian embryos?

    <p>Forming the eggshell during development</p> Signup and view all the answers

    How does the size and shape of eggs relate to nesting behaviors among cliff-nesting species?

    <p>Pointed eggs are evolved to reduce the likelihood of rolling off edges</p> Signup and view all the answers

    What characteristic is associated with the Hotshot Model of lek evolution?

    <p>Younger males cluster near experienced and dominant males.</p> Signup and view all the answers

    Which of the following best describes the purpose of bower complexity in bowerbirds?

    <p>Design helps attract mates by displaying social status.</p> Signup and view all the answers

    What does cooperative breeding primarily rely on?

    <p>The assistance of nonbreeding individuals to raise young.</p> Signup and view all the answers

    Which statement about extra-pair copulations (EPC) is true?

    <p>EPCs often contribute to high genetic diversity in populations.</p> Signup and view all the answers

    What is a key reason younger males delay dispersal and choose to help in cooperative breeding?

    <p>Improving their chances of future mating.</p> Signup and view all the answers

    Which characteristic is most common among obligate brood parasites?

    <p>They lay eggs in the nests of other species.</p> Signup and view all the answers

    What is the main benefit of the Female Preference Model in lekking behavior?

    <p>It allows females to evaluate males in large clusters.</p> Signup and view all the answers

    What evolutionary benefit might older male Purple Martins gain from extra-pair copulations?

    <p>Increased chances of mating due to earlier arrival.</p> Signup and view all the answers

    What advantage does kin selection provide in the context of cooperative breeding?

    <p>It enhances the reproductive success of related individuals.</p> Signup and view all the answers

    What is a significant characteristic of the yolk in bird eggs?

    <p>It contains both yellow yolk and white yolk.</p> Signup and view all the answers

    How does sperm storage in female birds benefit reproduction?

    <p>It allows for competition among sperm from different males.</p> Signup and view all the answers

    What is true regarding the testes of birds compared to mammals?

    <p>Bird testes can increase in size significantly during the breeding season.</p> Signup and view all the answers

    What adaptation allows certain waterfowl to have elongated reproductive organs?

    <p>Lymph-powered erections.</p> Signup and view all the answers

    In most birds, how is copulation typically accomplished?

    <p>By the male standing on the female's back and twisting their tails.</p> Signup and view all the answers

    Which feature distinguishes erectile mechanisms in the reproductive system of birds?

    <p>Fluid-based lymph-powered erections.</p> Signup and view all the answers

    Which bird species is an exception by having two functional ovaries?

    <p>Kiwis</p> Signup and view all the answers

    What role does the central latebra play in bird yolk structure?

    <p>It is a fluid center composed of vitellin.</p> Signup and view all the answers

    What mechanism allows most birds, lacking a penis, to mate?

    <p>Cloacal contact utilizing fast movements.</p> Signup and view all the answers

    How do female birds influence sperm competition?

    <p>By storing sperm from multiple males.</p> Signup and view all the answers

    What is the primary evolutionary purpose of the bowers created by bowerbirds?

    <p>To attract females by displaying male social status</p> Signup and view all the answers

    In the context of breeding systems, which statement correctly describes polygyny in birds?

    <p>Males mate with several females based on resource availability</p> Signup and view all the answers

    Which of the following models illustrates how females are attracted to clusters of males in leks?

    <p>Female Preference Model</p> Signup and view all the answers

    What percentage of offspring in Tree Swallows can commonly be fathered by males outside of the mated pair through extra-pair copulations?

    <p>As much as 50%</p> Signup and view all the answers

    How do helpers in cooperative breeding improve the chances of fledgling success?

    <p>By providing additional protection and provisioning</p> Signup and view all the answers

    What characteristic is associated with obligate brood parasites?

    <p>They are never seen caring for their own young</p> Signup and view all the answers

    Which of the following describes a key aspect of the Hotshot Model in lek evolution?

    <p>Inexperienced males gather near dominant males</p> Signup and view all the answers

    In what environment is cooperative breeding more likely to be favored?

    <p>Areas with low annual rainfall and high temperature variance</p> Signup and view all the answers

    What mechanism underlies the concept of reciprocal altruism in cooperative breeding?

    <p>Receiving help in future situations</p> Signup and view all the answers

    What is the function of cooperative displays in species like the Long-tailed Manakins?

    <p>To attract females through duet evaluations</p> Signup and view all the answers

    What differentiates why some bird species, like cliff-nesting birds, have evolved more pointed eggs?

    <p>To reduce chances of rolling off edges in their nesting sites</p> Signup and view all the answers

    Which factor is crucial for eggshells to effectively protect the developing embryo?

    <p>They need to withstand the weight of the incubating adult</p> Signup and view all the answers

    What does the term 'good genes' hypothesis in sexual selection suggest?

    <p>Males with superior genetic traits are more successful in reproduction</p> Signup and view all the answers

    What is the purpose of the albumen in avian eggs?

    <p>To supply water and protect the embryo by cushioning</p> Signup and view all the answers

    What role does sexual dimorphism play in avian species according to the content?

    <p>It signifies different reproductive roles and ecological specializations</p> Signup and view all the answers

    Which process best describes the formation of an egg from ovulation to shell formation?

    <p>Ovum is released, enters infundibulum for fertilization, then albumen and shell membranes are added</p> Signup and view all the answers

    What evolutionary advantage is suggested by the existence of leks in certain bird species?

    <p>Males congregate to maximize the chances of mating success despite low individual success</p> Signup and view all the answers

    What does intersexual selection primarily involve in the context of mate choice?

    <p>Females selecting mates based on specific male traits or displays</p> Signup and view all the answers

    What are the three extraembryonic membranes that the embryo in an avian egg possesses?

    <p>Chorion, amnion, allantois</p> Signup and view all the answers

    What does the term 'runaway selection' refer to in sexual selection theory?

    <p>Females preferentially choose males based on arbitrary traits, regardless of their benefits</p> Signup and view all the answers

    Study Notes

    Avian Reproductive Biology

    • Ovaries and Ovum:
      • Most birds have one functional ovary (left). Kiwis, raptors, some pigeons, gulls, and a few passerines have two.
      • Ovum (egg) is a mature reproductive cell.
      • Ovum development involves yolk layer formation and germ cell differentiation.
      • Yolk is composed of large (yellow) and small (white) globules.
      • A fluid center (vitellin) is encased in a membrane and separated from the albumen (egg white).
      • Albumen makes up ~50-70% of egg weight.

    Testes and Sperm

    • Testes:

      • Located in the body cavity at body temperature.
      • Most mammals have external testes to reduce heat that damages sperm.
      • Attached to the dorsal wall of the kidney.
      • Sperm production primarily happens at night (reduced heat).
      • Testis size can increase greatly during breeding season.
      • Sperm forms in seminiferous tubules, stored in seminal vesicles.
      • Sperm structure is similar to other vertebrates (head, midsection, tail).

    • Sperm Storage:

      • Female birds can store sperm in storage tubules to facilitate sperm competition.
      • Sperm of multiple males compete to fertilize the ovum.

    Genitalia

    • Penis:
      • Most birds lack a penis, unlike some reptiles and mammals.
      • Found only in Ratites (Paleognathae) and Landfowl/Waterfowl (Galloanseridae).
      • Modification of the cloaca wall is homologous to the mammalian/reptilian penis. Lost many times in evolution.
      • Cloaca: cavity for excretory and genital products.
      • Cloacal contact is the primary mating method.
      • Waterfowl have elaborate, spiral, lymph-powered penises.

    Copulation

    • Copulation Process:
      • Male typically mounts female.
      • Cloacas are brought into contact.
      • Some birds perform this mid-air (swifts).
      • Copulation is brief and frequent in most species (seconds). Some species (Goshawks) have frequent copulation.
      • Some birds have enlarged cloacal protuberances serving as male copulatory organs (esp. colonial nesting species - sperm competition).

    Eggs

    • Structure:

      • Avian eggs are cleidoic (closed).
      • Evolved from naked amniotic eggs, freeing reptiles from aquatic reproduction.
      • The shell calcifies (protecting) but prevents water absorption.
      • Albumen is essential for water packaging.
      • Yolk provides energy (lipids, proteins, water). Yolk percentage varies greatly across species. Yolk percentage correlates with chick helplessness (altricial) or mobility (precocial) at hatching.
      • Eggshells provide structural support and protection. Pores allow gas exchange.
      • Eggs vary incredibly in size and color (hummingbirds to elephant birds). Egg size correlates positively with body mass.
      • Eggs are typically oval but vary in shape; more pointed shapes are common in cliff nesters to prevent rolling.

    • Egg Development and Embryo:

      • Eggs are assembled as they pass through the oviduct (1 day - 1 week).
      • Fertilization occurs high in the oviduct.
      • Albumen, shell membranes, and shell form sequentially.
      • Egg provides a secure environment for embryonic development (passive gas exchange, uric acid excretion).
      • The embryo has three extraembryonic membranes (amnion, chorion, allantoic sac).

    Sexual Selection

    • Sexual Dimorphism:

      • Differences in male and female traits challenge natural selection's principles as best traits would be favored, regardless of sex.
      • Ecological or reproductive roles may lead to sexual differences.

    • Sexual Selection:

      • Differential reproductive success due to variation in mating success.
      • Heritable traits affecting mating ability are favored; more successful traits are passed down.

    Mate Choice

    • Processes:

      • Primarily driven by male-male competition (intrasexual) and female choice (intersexual).
      • Elaborate displays (morphological, behavioral) often evolve in males (costly, not survival-promoting, but reproductive benefits are gained).

    • Hypotheses:

      • Good genes: Genetic/physiological superiority.
      • Direct benefits: Material resources/protection.
      • Runaway selection: Arbitrary female preference.
      • Females assess mate quality to gain survival or reproductive benefits.
      • Ornaments/behaviors indicate male quality/resourcefulness.

    • Honest Advertising:

      • Traits reliably reflecting male fitness (e.g., brightness in house finches, longer displays in Bobolinks, larger fleshy combs in red junglefowl).

    Leks and Display Grounds

    • Leks: Communal display grounds where males gather.

      • No other resources than mating opportunities offered.
      • Single males may dominate copulation (promiscuous species).

    • Models of Lek Evolution:

      • Hot Spot: Males congregate where females are likely.
      • Hotshot: Males gather around experienced, attractive males.
      • Female Preference: Females prefer large clusters of males.

    • Examples: Black grouse, Great Argus, Andean Cock-of-the-Rock.

    Bowers

    • Bowerbirds Create elaborate display courts (bowers) out of sticks/grass.
    • Current evidence suggests that bowers show male quality.
    • Bower size and traits indicate good health and status (parasite load, body size).

    Breeding Systems

    • Diversity: Diverse breeding systems across bird species.

      • Trade-offs in current vs. future reproduction.

    • Monogamy: Predominant system; often socially monogamous (extra-pair copulations).

    • Polygyny: Males mate with multiple females (rare).

    • Polyandry: Females mate with multiple males (rare).

    Extra-Pair Mating

    • EPCs: Common across many socially monogamous species.
    • Potentially significant source of genetic contribution from males outside the pair bond.
    • Examples: Tree Swallows, Purple Martins.

    Cooperative Breeding

    • Helpers: Offspring provide care for parents' nest.
      • Sacrifice own reproduction (altruism).
      • Kin selection: helpers gain indirect fitness (via relatives).
      • Reciprocal altruism: trade help for future benefits.
    • Environmental constraints (low rainfall, high temp variance) may favor cooperative breeding.
    • Examples: Green Wood Hoopoes, Siberian Jays, White-fronted Bee-eaters.

    Brood Parasitism

    • Definition: Laying eggs in other birds' nests.
      • Facultative: Occasional; intraspecific or interspecific.
      • Obligate: Never raise their own young (cuckoos, cowbirds, honeyguides).
      • Co-evolutionary strategies have developed.

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    Description

    Explore the fascinating aspects of avian reproductive biology in this quiz. Learn about the unique aspects of bird ovaries, ovum development, testes, and sperm production. Test your knowledge on how these processes differ from other vertebrates.

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