Radiocesium (137Cs) concentrations were determined during 1974, 1981 and 1998 for seven species o... more Radiocesium (137Cs) concentrations were determined during 1974, 1981 and 1998 for seven species of fish inhabiting a stream (Steel Creek) contaminated by effluents from a nuclear reactor to examine the decline of this radionuclide in a natural ecosystem. Median 137Cs concentrations were highest in Micropterus salmoides (largemouth bass) during each year of the investigation (1974 = 6.67 Bq g(-1) dry wt. of whole body; 1981 = 3.72 Bq g(-1); 1998 = 0.35 Bq g(-1)), but no patterns of differences were observed among Aphredoderus sayanus (pirate perch), Esox americanus (redfin pickerel), Lepomis auritus (redbreast sunfish), L. gulosus (warmouth), L. punctatus (spotted sunfish), and Notropis cummingsae (dusky shiner). Results demonstrated a rapid decline in 137Cs within fish from Steel Creek during the 24-year period. For example, 137Cs concentrations in all fish species declined significantly among years, even after accounting for radioactive decay. The observed percent declines in 137Cs concentrations of individual species were 3-4 times greater between 1974 and 1981 compared to that expected by physical decay alone, and 2-3 times greater during 1981-1998. Ecological half-lives (EHLs) of 137Cs in fish ranged from 4.43 years in A. sayanus to 6.53 years in L. gulosus. The EHL for 137Cs in all fish species combined was 5.54 years. Current levels of 137Cs in fish from Steel Creek (1.16 Bq g(-1) dry wt. of whole body to below detection limits) indicate that the consumption of fish from this ecosystem poses little risk to humans and sensitive wildlife species. These results demonstrate the importance of incorporating the concept of ecological half-life into determinations concerning the length and severity of potential risks associated with radiocontaminants.
We studied the social organization and mating system of Peromyscus maniculatus in the Kananaskis ... more We studied the social organization and mating system of Peromyscus maniculatus in the Kananaskis Valley of Alberta by investigating both home range use and mating success. Radiotelemetry indicated ...
We examined the variation in relative testis size among northern populations of Peromyscus to tes... more We examined the variation in relative testis size among northern populations of Peromyscus to test if mice from populations with shorter breeding seasons had larger testes than mice from populations with longer breeding seasons. If natural selection on relative testes size in mammals is ultimately due to copulatory frequency and if sperm production is limited, then a decrease in the number of days in which a constant number of matings occurs should promote selection for larger testes. Relative testis size (testis length/body length) significantly varied among 10 populations of P. maniculatus and three populations of P. leucopus
We examined the effects of sibling matings upon reproductive performance among inbred and outbred... more We examined the effects of sibling matings upon reproductive performance among inbred and outbred laboratory colonies of Peromyscus maniculatus. The inbred colony was founded by 12 females collected from one locality in Alberta and bred for 20 generations, with 35–45 pairs each generation. The outbred colony consisted of first-generation mice born of wild-caught females from diverse areas in Alberta. Consistent with theoretical expectations, there were no differences in reproductive performance between sibling and control (outbred) pairs within the inbred colony of mice. In contrast, sibling pairs had significantly fewer young per litter than control pairs within the outbred colony. Reproductive performance measures (proportion breeding, days from pairing to first litter, number of litters, and total number of offspring produced) were also significantly lower among sibling pairs from the outbred colony than among sibling pairs from the inbred colony. Lastly, we predicted that reproductive performance of the control pairs from the outbred colony would be less than that of control pairs from the inbred colony, due to outbreeding depression. Contrary to our predictions, average litter survival rates were greatest among the outbred colony control pairs. We suggest that the benefits of inbreeding or outbreeding extend broadly across the inbreeding–outbreeding continuum in natural populations of northern Peromyscus.
There is a significant relationship between the intestine length (Y) and total body length (X) fo... more There is a significant relationship between the intestine length (Y) and total body length (X) for 11 species of freshwater fish (Y = 0.08X1.42). Sufficient variation exists about this relationship to indicate important differences among the species' diets. The diets for each species, ranked on a Trophic Index scale determined from literature data, are negatively rank order correlated with the mean relative intestine lengths (rs = -0.67). There is no significant rank order correlation between the Trophic Indices determined from data on stomach contents and the mean relative intestine lengths for fish from a single creek.
Joseph Grinnell designed the Natural History of the Vertebrates (NHV) course at the Museum of Ver... more Joseph Grinnell designed the Natural History of the Vertebrates (NHV) course at the Museum of Vertebrate Zoology, University of California at Berkeley, over 100 years ago and the course has changed little over these years. In this essay, I connect modern pedagogical and cognitive understandings of what we know leads to success among students to the course. This analysis reveals that the course continues to be successful because it has all the elements of a student-centered, active-learning class that leads to better cognitive gains, better retention, and importantly, proportionately better gains for students from underserved populations. This study will be important for advocates of teaching natural history in biology curriculum.
Radiocesium (137Cs) concentrations were determined during 1974, 1981 and 1998 for seven species o... more Radiocesium (137Cs) concentrations were determined during 1974, 1981 and 1998 for seven species of fish inhabiting a stream (Steel Creek) contaminated by effluents from a nuclear reactor to examine the decline of this radionuclide in a natural ecosystem. Median 137Cs concentrations were highest in Micropterus salmoides (largemouth bass) during each year of the investigation (1974 = 6.67 Bq g(-1) dry wt. of whole body; 1981 = 3.72 Bq g(-1); 1998 = 0.35 Bq g(-1)), but no patterns of differences were observed among Aphredoderus sayanus (pirate perch), Esox americanus (redfin pickerel), Lepomis auritus (redbreast sunfish), L. gulosus (warmouth), L. punctatus (spotted sunfish), and Notropis cummingsae (dusky shiner). Results demonstrated a rapid decline in 137Cs within fish from Steel Creek during the 24-year period. For example, 137Cs concentrations in all fish species declined significantly among years, even after accounting for radioactive decay. The observed percent declines in 137Cs concentrations of individual species were 3-4 times greater between 1974 and 1981 compared to that expected by physical decay alone, and 2-3 times greater during 1981-1998. Ecological half-lives (EHLs) of 137Cs in fish ranged from 4.43 years in A. sayanus to 6.53 years in L. gulosus. The EHL for 137Cs in all fish species combined was 5.54 years. Current levels of 137Cs in fish from Steel Creek (1.16 Bq g(-1) dry wt. of whole body to below detection limits) indicate that the consumption of fish from this ecosystem poses little risk to humans and sensitive wildlife species. These results demonstrate the importance of incorporating the concept of ecological half-life into determinations concerning the length and severity of potential risks associated with radiocontaminants.
We studied the social organization and mating system of Peromyscus maniculatus in the Kananaskis ... more We studied the social organization and mating system of Peromyscus maniculatus in the Kananaskis Valley of Alberta by investigating both home range use and mating success. Radiotelemetry indicated ...
We examined the variation in relative testis size among northern populations of Peromyscus to tes... more We examined the variation in relative testis size among northern populations of Peromyscus to test if mice from populations with shorter breeding seasons had larger testes than mice from populations with longer breeding seasons. If natural selection on relative testes size in mammals is ultimately due to copulatory frequency and if sperm production is limited, then a decrease in the number of days in which a constant number of matings occurs should promote selection for larger testes. Relative testis size (testis length/body length) significantly varied among 10 populations of P. maniculatus and three populations of P. leucopus
We examined the effects of sibling matings upon reproductive performance among inbred and outbred... more We examined the effects of sibling matings upon reproductive performance among inbred and outbred laboratory colonies of Peromyscus maniculatus. The inbred colony was founded by 12 females collected from one locality in Alberta and bred for 20 generations, with 35–45 pairs each generation. The outbred colony consisted of first-generation mice born of wild-caught females from diverse areas in Alberta. Consistent with theoretical expectations, there were no differences in reproductive performance between sibling and control (outbred) pairs within the inbred colony of mice. In contrast, sibling pairs had significantly fewer young per litter than control pairs within the outbred colony. Reproductive performance measures (proportion breeding, days from pairing to first litter, number of litters, and total number of offspring produced) were also significantly lower among sibling pairs from the outbred colony than among sibling pairs from the inbred colony. Lastly, we predicted that reproductive performance of the control pairs from the outbred colony would be less than that of control pairs from the inbred colony, due to outbreeding depression. Contrary to our predictions, average litter survival rates were greatest among the outbred colony control pairs. We suggest that the benefits of inbreeding or outbreeding extend broadly across the inbreeding–outbreeding continuum in natural populations of northern Peromyscus.
There is a significant relationship between the intestine length (Y) and total body length (X) fo... more There is a significant relationship between the intestine length (Y) and total body length (X) for 11 species of freshwater fish (Y = 0.08X1.42). Sufficient variation exists about this relationship to indicate important differences among the species' diets. The diets for each species, ranked on a Trophic Index scale determined from literature data, are negatively rank order correlated with the mean relative intestine lengths (rs = -0.67). There is no significant rank order correlation between the Trophic Indices determined from data on stomach contents and the mean relative intestine lengths for fish from a single creek.
Joseph Grinnell designed the Natural History of the Vertebrates (NHV) course at the Museum of Ver... more Joseph Grinnell designed the Natural History of the Vertebrates (NHV) course at the Museum of Vertebrate Zoology, University of California at Berkeley, over 100 years ago and the course has changed little over these years. In this essay, I connect modern pedagogical and cognitive understandings of what we know leads to success among students to the course. This analysis reveals that the course continues to be successful because it has all the elements of a student-centered, active-learning class that leads to better cognitive gains, better retention, and importantly, proportionately better gains for students from underserved populations. This study will be important for advocates of teaching natural history in biology curriculum.
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