8 public questions tagged with this topic.
r-selected species reproduce rapidly, produce many offspring, and provide little or no parental care.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Population Interactions - Mutualism and Amensalism
K-selected species invest in fewer offspring with high parental care, ensuring their survival.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Life History Variations and Population Interactions - Overview
Life-history theory emphasizes a trade-off between current reproductive effort and future reproduction. Energy devoted now to gametes, offspring, courtship, or care cannot also support growth, repair, immune defense, and survival to later breeding. Increasing present output may therefore reduce the number or quality of future offspring, while restrained investment can preserve residual reproductive value. Semelparity and iteroparity describe timing, whereas fecundity describes output. Long juvenile development can occur with either strategy. Ecologists therefore examine complete schedules of s
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 5
Ground squirrels are commonly represented by a Type II survivorship curve because their probability of dying is treated as approximately constant across much of life. On a semilogarithmic survivorship graph, a constant hazard produces a roughly straight decline. Real populations can depart from this ideal when juveniles, dispersers, or old individuals experience different risks, so the classification is a broad empirical approximation. A survivorship curve is built from a cohort life table by plotting the proportion alive at each age. Type I concentrates mortality late, Type II approximates a
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
K-selected organisms generally produce a small clutch because each offspring receives substantial resources. Energy that could create many propagules is instead invested in larger young, prolonged development, protection, or feeding. This trade-off tends to raise juvenile survival in stable, crowded environments where successful competition matters more than rapidly flooding an empty habitat with offspring. The r/K framework is best treated as a continuum. At one end, rapid development and many inexpensive offspring suit transient opportunities; at the other, slower development and greater inv
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
Survivorship describes the proportion of an original cohort that remains alive at successive ages, so it is shaped by age-specific mortality. Parental care can strongly alter that mortality by protecting eggs or young, provisioning food, and teaching avoidance behavior. Greater care commonly shifts deaths away from early life and produces the late-loss pattern associated with Type I curves, although many other environmental and genetic influences also matter. Life-history traits should be interpreted as correlated tendencies rather than rigid packages. Adult survival, juvenile mortality, body
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
“High survival until old age” for which of these is true for type i curve species. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Life-history traits reflect allocation among growth, maintenance, survival, and reproduction. Energy invested in many offspring cannot simultaneously be invested in large offspring, prolonged care, or future breeding, creating measurable trade-offs. The remaining alternatives—“High early mortality”, “No parental care”, “Low reproductive investment”—refer to different s
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
“Strong competitive ability” for k-strategists are more likely to exhibit. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Life-history traits reflect allocation among growth, maintenance, survival, and reproduction. Energy invested in many offspring cannot simultaneously be invested in large offspring, prolonged care, or future breeding, creating measurable trade-offs. The remaining alternatives—“Clumped dispersion”, “Type III survivorship”, “Early maturity”—refer to different states, processes,
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
