- A survivorship curve is drawn for a cohort and shows an approximately straight decline with age. This curve is most characteristic of which group?
Answer: Birds and other species with roughly constant mortality
Survivorship curves illustrate three basic mortality patterns in populations. Type I curves show low early mortality and high late-life mortality. Type II curves show an approximately straight decline with age on a linear scale, characteristic of birds and other species with roughly constant mortality where individuals face similar risks throughout life from factors like predation, disease, and accidents that don't strongly discriminate by age. Type III curves exhibit high juvenile mortality followed by lower adult mortality. The linear decline pattern indicates constant probability of death at any age, defining Type II survivorship.
- A student claims that a Type III survivorship curve indicates most individuals survive to old age and then die rapidly. Which survivorship curve type actually matches the student's description?
Answer: Type I
Survivorship curves represent different mortality patterns across age groups. The student incorrectly describes Type III as having most individuals survive to old age with rapid late death - this actually describes Type I survivorship. Type I curves are characterized by most individuals surviving to old age due to parental care and then dying rapidly due to senescence. Type II curves show constant mortality across ages. Type III curves exhibit high juvenile mortality with few individuals reaching adulthood. The student's description of high survival until old age followed by rapid mortality matches Type I survivorship, not Type III.
- A researcher notes that a species' survivorship is characterized by low mortality during early life due to parental care and medical intervention, but mortality increases dramatically at older ages. Which survivorship curve type is this?
Answer: Type I
Type I survivorship curves are characterized by low mortality rates during early and middle life stages, followed by a dramatic increase in mortality at older ages. This pattern is typical of species with extensive parental care, such as humans, other primates, and large mammals like elephants. The description explicitly states there is low mortality during early life due to parental care and medical intervention, with mortality increasing dramatically at older ages - this precisely matches the Type I pattern. Type II curves show constant mortality across all ages, while Type III curves show high early mortality followed by lower mortality for survivors. The combination of low early mortality and high late mortality definitively identifies this as Type I survivorship, making answer C correct.
- A researcher compares three populations: (1) humans in a city, (2) robins in a woodland, and (3) oysters in an estuary. Which pairing correctly matches each population to its most typical survivorship curve type?
Answer: Humans: Type I; Robins: Type II; Oysters: Type III
Survivorship curves illustrate three basic mortality patterns in populations. Type I curves show low early mortality and high late-life mortality, characteristic of humans in developed countries with medical care and parental investment. Type II curves demonstrate constant mortality rates across all ages, typical of many birds like robins that face consistent predation and environmental hazards throughout life. Type III curves exhibit high juvenile mortality followed by lower adult mortality, exemplified by oysters and other marine organisms that release many offspring with little care. The correct pairing matches each species with its typical survivorship pattern based on life history strategies.
- A cohort survivorship curve for a species of large mammal remains high until late life, then declines steeply. Which survivorship curve type is this?
Answer: Type I
Survivorship curves describe mortality patterns throughout an organism's lifespan. Type I curves are characterized by remaining high until late life and then declining steeply, typical of large mammals that provide extensive parental care ensuring high juvenile survival, with most individuals living through early and middle life stages before experiencing sharp mortality increases due to senescence and age-related physiological deterioration near their maximum lifespan. Type II curves show constant mortality across ages. Type III curves exhibit high juvenile mortality followed by lower adult mortality. The pattern of high survival until late-life decline defines Type I survivorship.
- A botanist studies a tree species that produces many seeds, but most seedlings die from drought and herbivory; mature trees have relatively high survival for decades. Which survivorship curve type best fits?
Answer: Type III (high early mortality)
Survivorship curves describe mortality patterns throughout an organism's lifespan. Type I curves show low early mortality and high late-life mortality, typical of species with extensive parental care. Type II curves demonstrate constant mortality rates across ages. Type III curves are characterized by extremely high juvenile mortality followed by relatively low adult mortality for survivors. Tree species that produce many seeds with most seedlings dying from drought and herbivory, but with mature trees surviving for decades, exemplify the Type III pattern where massive early mortality is followed by much better survival rates for individuals that successfully establish and reach maturity.
- A survivorship curve for Species Y shows a steep drop in survivorship between ages 0 and 1, followed by a much slower decline from ages 1 to 10. Which survivorship curve type is Species Y most likely to exhibit?
Answer: Type III (high juvenile mortality, lower mortality after maturity)
The survivorship curve described for Species Y shows a steep drop between ages 0 and 1, followed by a much slower decline from ages 1 to 10. This pattern is characteristic of Type III survivorship, where there is very high mortality in early life stages (the steep drop between ages 0 and 1) followed by relatively low mortality for individuals that survive past the vulnerable juvenile period (the slower decline from ages 1 to 10). Type I curves would show high survival in early life, not a steep drop, while Type II curves would show a constant rate of decline throughout life rather than the two distinct phases described. The dramatic early mortality followed by improved survival for older individuals definitively identifies this as Type III survivorship, making answer C correct.
- A survivorship curve is drawn for a cohort and shows a steep decline early in life followed by a flatter tail. This curve is most characteristic of which group?
Answer: Species with many offspring and little parental care
Survivorship curves describe mortality patterns throughout an organism's lifespan. Type I curves show low early mortality and high late-life mortality. Type II curves demonstrate constant mortality rates across ages. Type III curves show a steep decline early in life followed by a flatter tail, characteristic of species with many offspring and little parental care where most young die from predation, disease, or environmental stress, but those surviving the vulnerable early period then have improved survival prospects and can reproduce multiple times. This reproductive strategy results in the Type III survivorship pattern.
- In a seabird colony, the probability of dying appears roughly the same each year of life (juveniles and adults face similar annual risk). Which survivorship curve type is most consistent with this observation?
Answer: Type II (constant mortality rate across ages)
Survivorship curves represent different mortality patterns across age groups. Type I curves show low early mortality and high late-life mortality, typical of species with parental care. Type II curves demonstrate constant mortality rates across all ages, meaning the probability of death remains roughly the same whether an individual is young or old. Type III curves exhibit high juvenile mortality with lower adult mortality. When seabirds face similar annual mortality risk regardless of age (juveniles and adults have equal death probability), this represents the constant mortality pattern characteristic of Type II survivorship curves.
- A survivorship curve for a species is expected to be Type III. Which mortality pattern should be predicted?
Answer: Mortality is high early in life and decreases for survivors
Survivorship curves describe mortality patterns throughout an organism's lifespan. Type I curves show low early mortality and high late-life mortality. Type II curves demonstrate constant mortality rates across ages. Type III curves are characterized by mortality being high early in life and decreasing for survivors, where most deaths occur among juveniles due to predation, disease, or environmental stress, but individuals that survive the vulnerable early stages then face lower mortality rates throughout their remaining lifespan. This pattern of high early mortality followed by improved survival for those reaching maturity defines Type III survivorship.
- A species produces many offspring, provides little to no parental care, and most offspring die young. Which survivorship curve type best matches?
Answer: Type III
Survivorship curves illustrate three basic mortality patterns in populations. Type I curves show low early mortality and high late-life mortality, typical of species with parental care. Type II curves demonstrate constant mortality rates across ages. Type III curves are characterized by species that produce many offspring with little to no parental care, resulting in most offspring dying young due to predation, disease, or environmental stress, with only a small fraction surviving to reproductive maturity. This reproductive strategy of high fecundity with minimal parental investment leads to the Type III survivorship pattern.
- A population ecologist summarizes three idealized survivorship curves: one with late-life mortality (humans), one with constant mortality (many birds), and one with high early mortality (many fish/insects). Which curve type corresponds to the constant-mortality pattern?
Answer: Type II
Survivorship curves represent different mortality patterns across age classes in populations. The population ecologist correctly identifies three idealized patterns: late-life mortality (humans with Type I), constant mortality (many birds), and high early mortality (fish/insects). Type I curves show low early mortality and high late-life mortality. Type II curves are characterized by constant mortality rates across all ages, where the probability of death remains roughly equal throughout the lifespan due to factors affecting all age classes similarly. Type III curves exhibit high juvenile mortality followed by lower adult mortality.
- A survivorship curve remains high for most of the lifespan and then drops rapidly near the maximum age. Which type is it?
Answer: Type I
Survivorship curves represent different mortality patterns across age classes in populations. Type I curves are characterized by low mortality throughout most of the lifespan with a rapid decline only near the maximum age due to senescence, remaining high for most of life then dropping rapidly at the end. Type II curves show constant mortality rates across all ages, appearing as a straight declining line. Type III curves exhibit high juvenile mortality followed by lower adult mortality. The pattern of high survivorship maintained until late life followed by rapid decline describes the classic Type I survivorship curve.
- A survivorship curve for a species drops steeply at very young ages and then levels off for the remaining lifespan. Which type is it?
Answer: Type III
Survivorship curves illustrate mortality patterns throughout an organism's lifespan. Type I curves show low early mortality and high late-life mortality, remaining high through most of life then dropping steeply near maximum age. Type II curves demonstrate constant mortality rates, appearing as a straight declining line. Type III curves are characterized by extremely high juvenile mortality followed by lower adult mortality, creating a steep initial drop at very young ages followed by a leveling off for the remaining lifespan. This pattern of steep early decline then flattening describes the Type III survivorship curve.
- A lab population of fruit flies shows extremely high survival for the first half of life, then a rapid increase in mortality late in life due to aging. Which survivorship curve type does this resemble most?
Answer: Type I
Survivorship curves represent different mortality patterns across age classes. Type I curves are characterized by extremely high survival for early and middle life stages, followed by a rapid increase in mortality late in life due to aging and senescence processes. Type II curves show constant mortality across ages. Type III curves exhibit high juvenile mortality followed by lower adult mortality. Laboratory fruit fly populations, like other species with extensive parental care or protected environments, often demonstrate high early survival followed by age-related mortality increases, which resembles the Type I survivorship pattern most closely.
- A biologist finds that in a certain population, only 5% of individuals survive past the first month, but those that do often live for years. Which survivorship curve type is most consistent with this pattern?
Answer: Type III
Survivorship curves describe mortality patterns throughout an organism's lifespan. Type I curves show low early mortality and high late-life mortality. Type II curves demonstrate constant mortality rates across ages. Type III curves are characterized by extremely high juvenile mortality with only a small percentage (like 5%) of individuals surviving past the first critical period, but those that do survive the vulnerable early stages often live for years with much improved survival prospects. This pattern of massive early losses followed by better adult survival is most consistent with Type III survivorship.
- A cohort survivorship curve for a species of bird declines at an approximately constant rate over time. Which survivorship curve type is this?
Answer: Type II
Survivorship curves illustrate three basic mortality patterns in populations. Type I curves show low early mortality and high late-life mortality. Type II curves are characterized by declining at an approximately constant rate over time, appearing as a straight line on a linear plot because the same proportion of individuals dies each time period regardless of age, indicating constant mortality risk throughout the lifespan. Type III curves exhibit high juvenile mortality followed by lower adult mortality. Many bird species exemplify this constant mortality pattern where environmental hazards affect all age classes similarly, defining Type II survivorship.
- A wildlife biologist tracks survivorship in three species. Species X has high survival through early and middle life, followed by a steep decline in old age (e.g., many large mammals). Which survivorship curve type best matches Species X?
Answer: Type I (low early mortality, high mortality in old age)
Survivorship curves show the proportion of individuals surviving at each age in a population. Type I curves are characterized by high survival rates through early and middle life, followed by a sharp decline in survival during old age - this pattern is typical of large mammals like elephants, humans, and many primates that invest heavily in parental care. Type II curves show constant mortality rates across all ages, creating a diagonal line on a semi-log plot. Type III curves exhibit very high mortality in early life stages, but individuals that survive to adulthood have relatively low mortality rates thereafter. Species X, with its high survival through early and middle life followed by steep decline in old age, clearly exhibits a Type I survivorship pattern, making answer C correct.
- A population of wolves has low pup mortality due to strong pack care and protection, and most individuals survive until later life when mortality increases. Which survivorship curve type is most likely?
Answer: Type I
Survivorship curves represent different mortality patterns across age groups. Type I curves are characterized by low pup mortality due to strong pack care and protection, with most individuals surviving until later life when mortality increases due to age-related factors and senescence. Type II curves show constant mortality rates across all ages. Type III curves exhibit high juvenile mortality followed by lower adult mortality. Wolf populations with extensive parental care protecting young and most individuals living until old age exemplify the Type I survivorship pattern typical of social mammals with strong family structures and parental investment.
- A city ecologist studies an urban pigeon population and finds that the probability of dying is approximately the same each year regardless of age (juveniles, adults, and older birds have similar annual mortality risk). Which survivorship curve type best fits this pattern?
Answer: Type II (constant mortality rate across the lifespan)
Type II survivorship curves are characterized by a constant mortality rate throughout life, meaning individuals have approximately the same probability of dying at any age. This creates a straight diagonal line when plotting log(survivors) versus age. Type I curves show low mortality until old age, while Type III curves show very high juvenile mortality. The urban pigeon population described has similar annual mortality risk for juveniles, adults, and older birds - this constant mortality rate across all life stages is the defining characteristic of Type II survivorship. Answer B correctly identifies this as Type II survivorship. Many bird species, some lizards, and various invertebrates exhibit this pattern where death risk remains relatively constant throughout life.
