David V. Howe

Knowledge gain and behavioral change in citizen-science programs.

Citizen-science programs are often touted as useful for advancing conservation literacy, scientific knowledge, and increasing scientific-reasoning skills among the public. Guidelines for collaboration among scientists and the public are lacking and the extent to which these citizen-science initiatives change behavior is relatively unstudied. Over two years, we studied 82 participants in a three-day program that included education about non-native invasive plants and collection of data on the occurrence of those plants. Volunteers were given background knowledge about invasive plant ecology and trained on a specific protocol for collecting invasive plant data. They then collected data and later gathered as a group to analyze data and discuss responsible environmental behavior with respect to invasive plants. We tested whether participants without experience in plant identification and with little knowledge of invasive plants increased their knowledge of invasive species ecology, participation increased knowledge of scientific methods, and participation affected behavior. Knowledge of invasive plants increased on average 24%, but participation was insufficient to increase understanding of how scientific research is conducted. Participants reported increased ability to recognize invasive plants and increased awareness of effects of invasive plants on the environment, but this translated into little change in behavior regarding invasive plants. Potential conflicts between scientific goals, educational goals, and the motivation of participants must be considered during program design.

Evaluating the performance of volunteers in mapping invasive plants in public conservation lands.

Citizen science programs are touted as useful tools for engaging the public in science and for collecting important data for scientists and resource managers. To accomplish the latter, it must be shown that data collected by volunteers is sufficiently accurate and reliable. We engaged 119 volunteers over three years to map and estimate abundance of invasive plants in New York and New Jersey parklands. We tested their accuracy via collected pressed samples and by subsampling their transect points. We also compared the performances of volunteers and botanical experts. Our results support the notion that volunteer participation can enhance the data generated by scientists alone. We found that the quality of data collected might be affected by the environment in which the data are collected. We suggest that giving consideration to how people learn can not only help to achieve educational goals but can also help to produce more data to be used in scientific study.

Female choice linked to male dorsal fin height in a shortfin molly

Sexual selection is a possible mechanism of speciation. This could be true even in systems where female mate choice has not been clearly observed, because pre-existing biases may be expressed if female decision-making results in male trait evolution. In some mollies, males have enlarged dorsal fins and courtship display is the prevailing mating process. In others, male dominance is thought to play a greater role. We tested females of a species in the latter group, Poecilia mexicana, for consistent preference related to dorsal fin morphology. We found that females were biased toward larger dorsal fins. This latent preference could be an important driver in trait evolution.

Feeding Habits of Age-0 Striped Bass, Morone saxatilis, in the Mid-Hudson River Estuary: Temporal, Spatial, and Ontogenetic Variation

We quantified temporal and spatial variability in diets of 950 juvenile (age-0) striped bass in the Hudson River estuary. We used canonical correspondence analysis to assess the roles of temporal and spatial habitat variability in juvenile diet variation. We found that juvenile striped bass diets in the Hudson River were only modestly comparable to diets in other east coast estuaries. Among-year differences (51.4%) and spatial differences (41.9%) were substantially associated with juvenile striped bass diet. We found ontogeny (2.8%) and within-season variation (9.5%) to only weakly associate with diet variation. Our results indicate that an understanding of the temporal and spatial variation within the Hudson River estuary is vital in understanding variation in feeding by resident juvenile fish.

Female preference in the context of male–male interactions in Maylandia zebra of Lake Malawi

The mbuna cichlids of Lake Malawi are a diverse, monophyletic, and recently derived clade. Sexual selection is thought to have accelerated their rapid diversification, though the mechanism by which this has occurred remains unknown. In this study, we examine the effect that male–male interactions have on female preference. We first used a short interaction experiment as a proxy for male dominance. We then measured female preference for (1) a single, isolated male; (2) a group of three, highly ranked males, relative to a group of lower ranked males; and (3) a group of three, mixed-ranked males against a similar group of mixed-rank males. We found that male dominance was highly correlated with male standard length. Female preference for male standard length and for dominance rank was significant in both isolated and group interactions. However, females only showed preference for groups of interacting males when males were segregated by dominance rank, not when groups were composed of both dominant and subordinate males. The results suggest that male–male contests influence female mating decisions. By investigating the rules that dictate the outcomes of such interactions we can elucidate the role that behavior plays in the diversification of this species-rich lineage.

Male interactions in a group of Malaŵi cichlids

The haplochromine cichlids of the East African rift lakes comprise one of the most diverse radiations of vertebrates. The goal of the study was to investigate sexual selection in the Mbuna, a group of Lake Malaŵi haplochromine cichlids. In particular, the effects of male morphology, dominance behaviour, and territory were investigated in the context of female territory visits and male territory preference analyses. Female visits of males in the field were associated with aspects of male behaviour, body depth, and territory. Data from the laboratory suggest that males hold similar preferences for types of territory which to defend. It is suggested that male–male interaction should be given more attention in the study of the reproductive isolation and differential male mating success in the Mbuna cichlids of Lake Malaŵi.

Female Associative Behavior Accompanies Morphological Distinction in Two Panamanian Populations of the Molly Poecilia gilli (Kner)

ABSTRACT We investigated the associative behavior of the female molly (Pisces: Poeciliidae), Poecilia gilli (Kner), collected from two Panamanian populations—one from a clear running forest stream and the other from an impacted suburban stream. We tested the hypotheses that females would preferentially associate with males and females of their local population versus the foreign population and that males would prefer local females. We also tested the hypothesis that morphological distinctions between the two populations can be made. We found that females preferentially associated with local males but preferred neither local nor foreign females. Males exhibited no preference for females based on stream of origin. Dorsal fin height differed between populations but sex had no effect on this trait. Ecological factors or female preference could be responsible for this divergence, which could be reinforced by female preference for local males.

Photopigment Spectral Absorbance in Four Hudson River Fishes

ABSTRACT We measured the spectral absorbance of photoreceptor cells from four fish species common to the lower Hudson River—striped bass (Morone saxatilis), white perch (Morone americana), Atlantic silverside (Menidia menidia), and bluefish (Pomatomus saltatrix). Striped bass and white perch were dichromatic with maximum wavelength sensitivities around 530 nm and above 600 nm. Atlantic silverside had cones with peak absorbances at 400 nm, 449 nm, and 570 nm. The bluefish peak absorbances fell at 423 nm, 447 nm, 526 nm, and 564 nm.