Introduction: Perceived susceptibility to diseases influences intentions to undertake health prot... more Introduction: Perceived susceptibility to diseases influences intentions to undertake health protective measures. Methods: The study investigated perceived susceptibility of nasopharyngeal carcinoma (NPC) among Malaysians, focusing on their expressions of disease susceptibility before and after reading an NPC health pamphlet. Method: A total of 65 participants in Kuching and Kota Samarahan, Malaysia, aged 13 to 65, were interviewed on their perceptions of their risk of getting NPC. Results: The thematic analysis of the interviews revealed several levels of perceived susceptibility to NPC, namely, 1) not susceptible to NPC, 2) may be susceptible to NPC, 3) susceptible to NPC, and 4) not knowing much about susceptibility to NPC. The expressions the participants used revolved around “living a healthy life”, “second-hand smoker”, “polluted air” and “eat preserved or salted food”, indicating perceived risk factors of NPC. Conclusion: Some mentioned family history and ethnic background ...
Recent studies have suggested that the caudal medial entorhinal cortex (cMEC) is specialized for ... more Recent studies have suggested that the caudal medial entorhinal cortex (cMEC) is specialized for path integration and spatial navigation. However, cMEC is part of a brain system that supports episodic memory for both spatial and nonspatial events, and so may play a role in memory function that goes beyond navigation. Here, we used receiver operating characteristic analysis to investigate the role of the cMEC in familiarity and recollection processes that underlie nonspatial recognition memory in rats. The results indicate that cMEC plays a critical and selective role in recollection-based performance, supporting the view that cMEC supports memory for the spatial and temporal context in which events occur.
Here we show that demands associated with brood parasitism have favored sophisticated cognitive a... more Here we show that demands associated with brood parasitism have favored sophisticated cognitive abilities in female brown-headed cowbirds. We discovered that cowbirds can use the rate at which eggs are added to a nest across days to assess the readiness of the nest for incubation, which would allow them to synchronize laying with the host and avoid nests where incubation has most likely commenced. In three experiments, cowbirds investigated and laid eggs in artificial nests that differed in the number of eggs they contained. Across days, we added eggs to nests at different rates to simulate differences in the timing of reproduction of the hosts. Cowbirds avoided a nest if the number of eggs that had been added was less than the number of days that had elapsed. The ability of females to remember egg number and compare changes in egg number across days allows them to select nests most suitable for parasitism.
Introduction 1 Chapter One. Effect of ancestry on behavioral variation in two species of howler m... more Introduction 1 Chapter One. Effect of ancestry on behavioral variation in two species of howler monkeys (Alouatta pigra and A. palliata) and their hybrids 10 Chapter Two. Activity patterns are influenced by ancestry and habitat disturbance in Alouatta pigra, A. palliata, and their hybrids 50 Chapter Three. Ancestry, but not kinship, influences prosocial behavior in Alouatta pigra, A. palliata, and their hybrids 91 Conclusions 127 vii LIST OF TABLES TABLE 1.1 Summary of social system differences between Alouatta pigra and A. palliata 1.2 Summary of groups sampled during study period 2.1 Multiple regression results for activity patterns across all taxa 2.2 Differences among taxonomic categories in activity patterns 2.3 Multiple regression results for activity patterns among hybrids 3.1 Microsatellite markers used in analysis of hybrid index and relatedness 3.2 Mean group hybrid index and relatedness viii LIST OF FIGURES FIGURE 1.1 Map of study sites 1.2 Frequency of being <5m across taxonomic and sex categories 1.3 Rates of female-female affiliation across taxonomic categories 2.1 Activity budgets across taxonomic categories 2.2 Distance traveled per hour across taxonomic categories 2.3 Activity budgets among hybrids sharing a forest fragment versus living alone 2.4 Average home range across taxonomic categories 3.1 Genetic hybrid index 3.2 Porportion of time <5m among female-female dyads split by hybrid index 3.3 Rates of female-female affiliation split by hybrid index ix
We conducted a series of experiments designed to examine the stimuli to which female brown-headed... more We conducted a series of experiments designed to examine the stimuli to which female brown-headed cowbirds (Molothrus ater) attend when selecting a nest for parasitism. We gave hand-reared juvenile and wild-caught adult females opportunities to assess nests containing different numbers and types of mock eggs. We measured female interest in nests by recording the number of times they approached nests (experiments 1 and 2), and also, we maintained 5 groups of adult and 2 groups of juvenile females in outdoor aviaries where we could measure patterns of laying in nests (experiment 3). Results from both types of experiments were similar. Females of both age classes preferred nests with eggs over nests without eggs, nests containing 3 eggs to nests containing 1 egg, small eggs to medium sized eggs, and medium eggs to large eggs. In addition, there was an age-related effect in how females responded to a nest that already contained a cowbird egg. Adult females avoided nests containing cowbird eggs, whereas juveniles preferred these parasitized nests. Taken together, the results provide evidence of the adaptive nature of decision processes involved in host nest selection.
The relatively fixed vocal structure of nonhuman primates stands in stark contrast to humans. How... more The relatively fixed vocal structure of nonhuman primates stands in stark contrast to humans. However, primate vocal-plasticity studies are particularly limited by ethical and logistic constraints. As an alternative approach, we take advantage of a confirmed howler hybrid zone (Alouatta palliata × A. pigra) to compare the effects of genetic ancestry and experience on vocal variation. Deviations from a tight phenotypeancestry correlation can indicate potential plasticity. We also tested whether temporal features (e.g., syllable number, calling rate) show more plasticity than acoustic features (e.g., peak frequency, bandwidth) which might be morphologically constrained. Using 29 microsatellite markers, most hybrid male subjects fell at the extremes of the genetic ancestry distribution, consistent with the entire population's distribution. We then analyzed 182 howling bouts and 231 loud call recordings from 33 male hybrid and purebred subjects from sympatric and allopatric populations. Acoustic features of hybrid calls clustered with calls from genetically similar purebred males, and calls
Comparing vocalizations across species is useful for understanding acoustic variation at mechanis... more Comparing vocalizations across species is useful for understanding acoustic variation at mechanistic and evolutionary levels. Here, we take advantage of the divergent vocalizations of two closely related howler monkey species (Alouatta pigra and A. palliata) to better understand vocal evolution. In addition to comparing multiple acoustic and temporal features of roars and the calling bouts in which they are produced, we tested several predictions. First, A. pigra should have roars with lower fundamental frequency and lower formant dispersion because they are larger than A. palliata and have a larger hyoid apparatus. Second, A. pigra should have faster calling rates, longer roars, longer bouts, and exaggerated call features linked to vocal effort (e.g., nonlinear phenomena and emphasized frequencies) because they are the more aggressive species during intergroup encounters. We found significant interspecific differences supporting our predictions in every tested parameter of roars an...
Conspicuous colored patches on animals often serve as sexually selected signals that advertise ma... more Conspicuous colored patches on animals often serve as sexually selected signals that advertise male quality. Such colored traits facilitate assessment of risks associated with a specific contest or benefits associated with a specific mate choice. Here, we investigate whether a colored patch of skin on the chests of male geladas (Theropithecus gelada) is a sexually selected signal. Specifically, we examine the relationship between color (redness), social status (a proxy for reproductive success), and age. We use observational data from known individuals from a population of wild geladas living in Ethiopia. We digitally quantified chest color using a previously-validated method for measuring color under field conditions. Results from this study are consistent with the hypothesis that redness is a quality signal in males. Baseline color correlates with status even when controlling for age. Indeed, males with redder chests were members of "better" groups: 1) leader males-the only males with reproductive access to females-had the reddest chests, and 2) within leader males, males with large units (>6 females) had redder chests than males with small units. At present, we are unable to address whether male chest Int J Primatol
Social differences between primate species may result from both flexible responses to current con... more Social differences between primate species may result from both flexible responses to current conditions or fixed differences across taxa, yet we know little about the relative importance of these factors. Here, we take advantage of a naturally occurring hybrid zone in Tabasco, Mexico to characterize the variation in social structure among two endangered howler monkey species, Alouatta pigra and A. palliata, and their hybrids. Work in pure populations has suggested that A. pigra females maintain closer proximity, exhibit higher rates of affiliation, and lower rates of agonism than A. palliata females, but we do not know what accounts for this difference. Using identical data collection and analysis methods across three populations, we first seek to confirm previously reported interspecific differences in social structure across all sexes. We next examine: (1) how female social relationships changed with ancestry (by comparing pure and hybrid individuals); (2) how female social relationships changed with group size (A. pigra have smaller groups than A. palliata); and (3) whether female social relationships differed between two taxonomic groups within a single forest fragment (thus controlling for ecological variation). We confirmed previously described species differences, including closer proximity among females than among males in all populations. We also found that smaller groups maintained closer proximity. However, even after accounting for variation in group size, A. pigra females had closer proximity and more affiliation than A. palliata females. Furthermore, differences between pigra-like and palliata-like hybrids paralleled differences between pure populations and persisted even after controlling for ecological variation. Together, our results suggest that flexibility cannot account for all of the social differences between A. pigra and A. palliata and indicate an important genetic component in primate social behavior. Am.
Up until now in this course, we have been primarily concerned with simplifying algebraic expressi... more Up until now in this course, we have been primarily concerned with simplifying algebraic expressions. That is, we have used various methods to rewrite expressions in algebraically equivalent, and usually simpler, ways. Many of these expressions contained one variable, but some contained two or more variables. In this section we will begin solving equations, and we will continue to solve equations throughout the year. Almost all of the algebra that we have already learned will be applicable, and there are a few additional rules that we can use when solving equations. For now, the equations that we will solve will involve one variable only. Let's start by defining what it means to solve an equation: Definitions: To solve a one-variable equation means to find all values of the variable that make the equation into a true statement. The solution to the equation is the set of such values.
Introduction: Perceived susceptibility to diseases influences intentions to undertake health prot... more Introduction: Perceived susceptibility to diseases influences intentions to undertake health protective measures. Methods: The study investigated perceived susceptibility of nasopharyngeal carcinoma (NPC) among Malaysians, focusing on their expressions of disease susceptibility before and after reading an NPC health pamphlet. Method: A total of 65 participants in Kuching and Kota Samarahan, Malaysia, aged 13 to 65, were interviewed on their perceptions of their risk of getting NPC. Results: The thematic analysis of the interviews revealed several levels of perceived susceptibility to NPC, namely, 1) not susceptible to NPC, 2) may be susceptible to NPC, 3) susceptible to NPC, and 4) not knowing much about susceptibility to NPC. The expressions the participants used revolved around “living a healthy life”, “second-hand smoker”, “polluted air” and “eat preserved or salted food”, indicating perceived risk factors of NPC. Conclusion: Some mentioned family history and ethnic background ...
Recent studies have suggested that the caudal medial entorhinal cortex (cMEC) is specialized for ... more Recent studies have suggested that the caudal medial entorhinal cortex (cMEC) is specialized for path integration and spatial navigation. However, cMEC is part of a brain system that supports episodic memory for both spatial and nonspatial events, and so may play a role in memory function that goes beyond navigation. Here, we used receiver operating characteristic analysis to investigate the role of the cMEC in familiarity and recollection processes that underlie nonspatial recognition memory in rats. The results indicate that cMEC plays a critical and selective role in recollection-based performance, supporting the view that cMEC supports memory for the spatial and temporal context in which events occur.
Here we show that demands associated with brood parasitism have favored sophisticated cognitive a... more Here we show that demands associated with brood parasitism have favored sophisticated cognitive abilities in female brown-headed cowbirds. We discovered that cowbirds can use the rate at which eggs are added to a nest across days to assess the readiness of the nest for incubation, which would allow them to synchronize laying with the host and avoid nests where incubation has most likely commenced. In three experiments, cowbirds investigated and laid eggs in artificial nests that differed in the number of eggs they contained. Across days, we added eggs to nests at different rates to simulate differences in the timing of reproduction of the hosts. Cowbirds avoided a nest if the number of eggs that had been added was less than the number of days that had elapsed. The ability of females to remember egg number and compare changes in egg number across days allows them to select nests most suitable for parasitism.
Introduction 1 Chapter One. Effect of ancestry on behavioral variation in two species of howler m... more Introduction 1 Chapter One. Effect of ancestry on behavioral variation in two species of howler monkeys (Alouatta pigra and A. palliata) and their hybrids 10 Chapter Two. Activity patterns are influenced by ancestry and habitat disturbance in Alouatta pigra, A. palliata, and their hybrids 50 Chapter Three. Ancestry, but not kinship, influences prosocial behavior in Alouatta pigra, A. palliata, and their hybrids 91 Conclusions 127 vii LIST OF TABLES TABLE 1.1 Summary of social system differences between Alouatta pigra and A. palliata 1.2 Summary of groups sampled during study period 2.1 Multiple regression results for activity patterns across all taxa 2.2 Differences among taxonomic categories in activity patterns 2.3 Multiple regression results for activity patterns among hybrids 3.1 Microsatellite markers used in analysis of hybrid index and relatedness 3.2 Mean group hybrid index and relatedness viii LIST OF FIGURES FIGURE 1.1 Map of study sites 1.2 Frequency of being <5m across taxonomic and sex categories 1.3 Rates of female-female affiliation across taxonomic categories 2.1 Activity budgets across taxonomic categories 2.2 Distance traveled per hour across taxonomic categories 2.3 Activity budgets among hybrids sharing a forest fragment versus living alone 2.4 Average home range across taxonomic categories 3.1 Genetic hybrid index 3.2 Porportion of time <5m among female-female dyads split by hybrid index 3.3 Rates of female-female affiliation split by hybrid index ix
We conducted a series of experiments designed to examine the stimuli to which female brown-headed... more We conducted a series of experiments designed to examine the stimuli to which female brown-headed cowbirds (Molothrus ater) attend when selecting a nest for parasitism. We gave hand-reared juvenile and wild-caught adult females opportunities to assess nests containing different numbers and types of mock eggs. We measured female interest in nests by recording the number of times they approached nests (experiments 1 and 2), and also, we maintained 5 groups of adult and 2 groups of juvenile females in outdoor aviaries where we could measure patterns of laying in nests (experiment 3). Results from both types of experiments were similar. Females of both age classes preferred nests with eggs over nests without eggs, nests containing 3 eggs to nests containing 1 egg, small eggs to medium sized eggs, and medium eggs to large eggs. In addition, there was an age-related effect in how females responded to a nest that already contained a cowbird egg. Adult females avoided nests containing cowbird eggs, whereas juveniles preferred these parasitized nests. Taken together, the results provide evidence of the adaptive nature of decision processes involved in host nest selection.
The relatively fixed vocal structure of nonhuman primates stands in stark contrast to humans. How... more The relatively fixed vocal structure of nonhuman primates stands in stark contrast to humans. However, primate vocal-plasticity studies are particularly limited by ethical and logistic constraints. As an alternative approach, we take advantage of a confirmed howler hybrid zone (Alouatta palliata × A. pigra) to compare the effects of genetic ancestry and experience on vocal variation. Deviations from a tight phenotypeancestry correlation can indicate potential plasticity. We also tested whether temporal features (e.g., syllable number, calling rate) show more plasticity than acoustic features (e.g., peak frequency, bandwidth) which might be morphologically constrained. Using 29 microsatellite markers, most hybrid male subjects fell at the extremes of the genetic ancestry distribution, consistent with the entire population's distribution. We then analyzed 182 howling bouts and 231 loud call recordings from 33 male hybrid and purebred subjects from sympatric and allopatric populations. Acoustic features of hybrid calls clustered with calls from genetically similar purebred males, and calls
Comparing vocalizations across species is useful for understanding acoustic variation at mechanis... more Comparing vocalizations across species is useful for understanding acoustic variation at mechanistic and evolutionary levels. Here, we take advantage of the divergent vocalizations of two closely related howler monkey species (Alouatta pigra and A. palliata) to better understand vocal evolution. In addition to comparing multiple acoustic and temporal features of roars and the calling bouts in which they are produced, we tested several predictions. First, A. pigra should have roars with lower fundamental frequency and lower formant dispersion because they are larger than A. palliata and have a larger hyoid apparatus. Second, A. pigra should have faster calling rates, longer roars, longer bouts, and exaggerated call features linked to vocal effort (e.g., nonlinear phenomena and emphasized frequencies) because they are the more aggressive species during intergroup encounters. We found significant interspecific differences supporting our predictions in every tested parameter of roars an...
Conspicuous colored patches on animals often serve as sexually selected signals that advertise ma... more Conspicuous colored patches on animals often serve as sexually selected signals that advertise male quality. Such colored traits facilitate assessment of risks associated with a specific contest or benefits associated with a specific mate choice. Here, we investigate whether a colored patch of skin on the chests of male geladas (Theropithecus gelada) is a sexually selected signal. Specifically, we examine the relationship between color (redness), social status (a proxy for reproductive success), and age. We use observational data from known individuals from a population of wild geladas living in Ethiopia. We digitally quantified chest color using a previously-validated method for measuring color under field conditions. Results from this study are consistent with the hypothesis that redness is a quality signal in males. Baseline color correlates with status even when controlling for age. Indeed, males with redder chests were members of "better" groups: 1) leader males-the only males with reproductive access to females-had the reddest chests, and 2) within leader males, males with large units (>6 females) had redder chests than males with small units. At present, we are unable to address whether male chest Int J Primatol
Social differences between primate species may result from both flexible responses to current con... more Social differences between primate species may result from both flexible responses to current conditions or fixed differences across taxa, yet we know little about the relative importance of these factors. Here, we take advantage of a naturally occurring hybrid zone in Tabasco, Mexico to characterize the variation in social structure among two endangered howler monkey species, Alouatta pigra and A. palliata, and their hybrids. Work in pure populations has suggested that A. pigra females maintain closer proximity, exhibit higher rates of affiliation, and lower rates of agonism than A. palliata females, but we do not know what accounts for this difference. Using identical data collection and analysis methods across three populations, we first seek to confirm previously reported interspecific differences in social structure across all sexes. We next examine: (1) how female social relationships changed with ancestry (by comparing pure and hybrid individuals); (2) how female social relationships changed with group size (A. pigra have smaller groups than A. palliata); and (3) whether female social relationships differed between two taxonomic groups within a single forest fragment (thus controlling for ecological variation). We confirmed previously described species differences, including closer proximity among females than among males in all populations. We also found that smaller groups maintained closer proximity. However, even after accounting for variation in group size, A. pigra females had closer proximity and more affiliation than A. palliata females. Furthermore, differences between pigra-like and palliata-like hybrids paralleled differences between pure populations and persisted even after controlling for ecological variation. Together, our results suggest that flexibility cannot account for all of the social differences between A. pigra and A. palliata and indicate an important genetic component in primate social behavior. Am.
Up until now in this course, we have been primarily concerned with simplifying algebraic expressi... more Up until now in this course, we have been primarily concerned with simplifying algebraic expressions. That is, we have used various methods to rewrite expressions in algebraically equivalent, and usually simpler, ways. Many of these expressions contained one variable, but some contained two or more variables. In this section we will begin solving equations, and we will continue to solve equations throughout the year. Almost all of the algebra that we have already learned will be applicable, and there are a few additional rules that we can use when solving equations. For now, the equations that we will solve will involve one variable only. Let's start by defining what it means to solve an equation: Definitions: To solve a one-variable equation means to find all values of the variable that make the equation into a true statement. The solution to the equation is the set of such values.
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