01:119:115 Lecture Notes - Lecture 21: Species Problem, Reproductive Isolation, Dendrobium

• School: Rutgers University
• Department: Biological Science
• Course: 01:119:115
• Professor: Daniel Stern Cardinale

Document Summary

Dendrobium, genus of orchids-flower on different days, only open for. 1 day: behavioral isolation: species-unique enable mate recognition, ex. Common in aquatic organisms release gametes into water: prozygotic barriers: operate after fertilization occurs, reduced hybrid viability: embryo dies early in development, ex. Overlapping salamander species sometimes hybridize, rarely develop: reduced hybrid fertility: hybrids are viable, but sterile or low fertility, most likely due to problems during meiosis, ex. Mule-female horse (2n=64) + male donkey (2n=62: hybrid breakdown: 1st generation hybrids are viable and fertile, hybrids can mate with each other or parent species, resulting offspring are infertile or frail. Crickets in hawaiian islands: chance events: random events can isolate sub-populations, ex. North american apple maggot fly: habitat isolation temporal isolation postzygotic barriers, extremely common. High species diversity: low environmental diversity high environmental diversity rapid diversification, environmental change change selective pressures biological change, ex. Cambrian explosion: 542-511 mya-relatively sudden appearance of many new phyla in fossil record: ex.