Lecture 19: Reproduction I

Question 1

asexual reproduction

Answer 1

mode of reproduction that does not involve the fusion of gametes (sex cells) or genetic material from two parents

Question 2

examples of asexual reproduction

Answer 2

budding, fragmentation, parthenogenesis

Question 3

budding

Answer 3

• new individuals arise as an outgrowth (bud) from parent

Question 4

fragmentation

Answer 4

• fragments of multicellular organisms can become complete organisms

Question 5

budding examples

Answer 5

hydra, yeast, corals

Question 6

fragmentation examples

Answer 6

planarians, sea stars, sponges

Question 7

parthenogenesis

Answer 7

• a form of asexual reproduction where offspring develop from unfertilized eggs
• development of offspring from unfertilized eggs
• typically ameiotic (lack of meiosis), leading to clones
• can be obligate (the only mode of reproduction) or cyclical (alternates with sexual reproduction)

Question 8

examples of parthenogenesis

Answer 8

aphids: tiny insects capable of producing genetically identical offspring
lizards: certain species like the whiptail lizard, rely solely on parthenogenesis
water fleas: parthenogenesis is part of their reproductive cycle

Question 9

sex is

Answer 9

complicated, costly, and dangerous

Question 10

sex and recombination may be advantageous in

Answer 10

changing environments and to evade pathogens/parasites

Question 11

sexual reproduction cycle in rodents

Answer 11

• start with an adult male and female mating
• involves meiosis, where cells divide to produce haploid sperm and eggs
• fertilization occurs, forming a diploid zygote
• growth follows, leading to new adult organisms

Question 12

monoecious organisms

Answer 12

not all sexually reproducing animals

Question 13

simultaneous monoecious stage

Answer 13

both organs are functional at the same time, enabling self-fertilization

Question 14

sequential monoecious stage

Answer 14

organisms switch between male and female stages, but not at the same time

Question 15

sex determination

Answer 15

biological process that decides whether an organism develops as male, female, or sometimes both

Question 16

variation

Answer 16

natural differences or diversity in traits, such as physical characteristics, that exist within members of a single species

Question 17

example of variation

Answer 17

lizards exhibit unique patterns and colors

• butterfly, bird, fish

Question 18

sex

Answer 18

• a distinction based on the type of gametes produced by an individual

Question 19

generally, organisms are described as

Answer 19

male or female

Question 20

sex is a binary that ignores the existence of

Answer 20

intersex phenotypes which are common in nature

Question 21

gender

Answer 21

• a social construct used to describe traits associated with the binary sexes
• culturally specific
• can reflect individual identity and societally imposed expectations

Question 22

an alternative hypothesis for the evolution of same-sex sexual behavior in animals

Answer 22

’ same sex behavior is something that has been observed in many species and has puzzled biologists as it doesn’t directly lead to reproduction
- authors of the article argue that the assumption of different-sex sexual behavior as the ancestral or “default” condition for animals is flawed; they suggest that SSB could be a natural and neutral part of the spectrum of sexual behaviors, rather than an anomaly requiring explanation
- this perspective encourages scientists to reconsider biases and assumption in the study of animal behavior, promoting a broader and more inclusive understanding of sexual strategies in evolution

Question 23

same- sex sexual behavior

Answer 23

sexual interactions or activities between individuals of the same sex within a species

Question 24

species exhibiting same-sex sexual behavior

Answer 24

• recorded observations in over 1500 species
• sea urchins, bats, snails, squids, snakes, various birds, dragonflies, beetles, cows, starfish, toads, worms, fish, and horseshoe crabs

Question 25

hypothesis of ancestral DSB

Answer 25

suggests that different sex behavior was the original or default sexual behavior in early animals, and any same sex behavior evolved later as a secondary trait

Question 26

hypothesis of indiscriminate sexual behavior

Answer 26

proposes that early animals were more likely to exhibit indiscriminate sexual behavior, meaning they didn't have a strong preference for same or different sex interactions; over time, specialized behaviors evolved in some species from this more flexible starting point