Population structure and reproductive period of whitebelly prawn Nematopalaemon schmitti (Holthuis 1950) (Decapoda: Caridea: Palaemonidae) on the southeastern coast of Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Population features of the spider crab Acanthonyx scutiformis (Dana 1851) (Crustacea, Majoidea, Epialtidae) associated with rocky-shore algae from southeastern Brazil.

Acanthonyx scutiformis, an endemic species in the Brazilian coast, is commonly found in intertidal rocky-shore algal communities. This study analyzes the population biology of A. scutiformis from Ubatuba region. A total of 371 specimens were collected over one year. Size range was 4.2[long dash]12.7 mm CW (carapace width) for females and 3.7[long dash]15.8 mm CW for males. Females predominated in intermediate size classes, whereas males prevailed in the largest ones. The estimated size when 50% crabs were mature was 10.7 mm CW for males and 8.9 mm CW for females. Sex ratio varied among the demographic groups. The processes that influence A. scutiformis population structure can be related to the different times males and females reach sexual maturity and probably to the distinct predation pressures on each sex during the adult phase.

Biology of Isopisthus parvipinnis: an abundant sciaenid species captured bycatch during sea-bob shrimp fishery in Brazil

A pesca de arrasto é o método mais comum de captura de camarão. Esta técnica causa impactos negativos na fauna demersal devido ao grande número de animais que são capturados acidentalmente e que geralmente são devolvidos mortos ao mar. As conseqüências desta metodologia de pesca e os aspectos biológicos das espécies envolvidas são pouco estudados, especialmente no Nordeste do Brasil. Este estudo tem como objetivo mostrar aspectos biológicos de Isopisthus parvipinnis (tortinha) capturada como fauna acompanhante da pesca do camarão sete barbas (Xiphopenaeus kroyeri) na região de Ilhéus, no estado da Bahia, Brasil. Um total de 1290 indivíduos foram capturados em coletas mensais, em três pontos de coleta distintos, de março de 2003 a fevereiro de 2005. O índice de dispersão de Morisita padronizado sugere que a espécie, na área analisada, apresenta uma distribuição agregada. O número de indivíduos variou significativamente entre as estações do ano (p < 0,0001), sendo maior durante o inverno. O comprimento estimado de primeira maturação (L50) foi de 159 mm, sendo que 95% dos indivíduos capturados estavam abaixo deste valor. A razão sexual encontrada foi de 1,5 machos para cada fêmea. Quanto à dieta, foram identificadas 10 categorias alimentares, sendo que Decapoda Dendobranchiata foi a mais importante em freqüência numérica e de ocorrência. Este fato sugere que Isopisthus parvipinnis é uma espécie carnívora, com tendência a carcinofagia, ao menos nos indivíduos jovens.

Population dynamics of Lucilia eximia (Dipt., Calliphoridae)

The theoretical dynamics of experimental populations of Lucilia eximia was investigated as an attempt to understand its population biology. Specifically the population dynamics of L. eximia was analysed by means of a mathematical model that incorporates fecundity and survival as density-dependent demographic parameters in discrete time. The sensitivity of these parameters to changes in the magnitude was also investigated. The mathematical model applied to experimental populations of L. eximia predicts a theoretical one-point equilibrium for immatures. The population dynamics of L. eximia is compared to the dynamics of Chrysomya species and Cochliomyia macellaria.

Reproductive Plasticity in the Speckled Crab Arenaeus cribrarius (Decapoda, Brachyura, Portunidae) Associated with a Population Decline

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Popularion biology of abdominant fish species of the Santa Bárbara river, a tributary of the Nova Avanhandava reservoir (low Tietê river, São Paulo State, Brazil)

The aim of this study is to characterize some population biology parameters of P. squamosissimus, A. altiparanae and S. maculatus, the dominant fish species of the Santa Bárbara river, a tributary of the Nova Avanhandava reservoir, low Tietê river. Fish samplings were performed monthly between September/2002 and August/2003, using gill nets with different mesh sizes. Females of all species have larger standard lengths than males (Mann-Whitney, p < 0.0001), and are more frequent in superior size classes (Kolmogorov-Smirnov, p < 0.0001). All populations presented isometric growth, but differences between males and females were observed. Only P. squamosissimus presented a gender ratio different from 1:1, with a higher proportion of males (1:2, X2, p < 0.05). The onset of gonadal maturation occurs at 15 cm in P. squamosissimus, 9 cm in S. maculatus and at 8.9 cm in A. altiparanae. In all species populations, the adults predominate over juveniles. The allometric condition factor (K) of P. squamosissimus and S. maculatus presented higher values in the periods from March-May and June-August, and A. altiparanae in the period from March-May (Kruskal-Wallis, p < 0.05). These results indicate that the populations successfully exploit the lentic environment, and present life cycle tactics adapted to their particular means of environment occupation.

Population parameters of the smooth lantern shark, Etmopterus pusillus, in southern Portugal (NE Atlantic)

Etmopterus pusillus is a deep water lantern shark with a widespread global distribution that is caught in large quantities in some areas, but is usually discarded due to the low commercial value. In this work, the population biology was studied and life history parameters determined for the first time in this species. Age was estimated from sections of the second dorsal spine and validated by marginal increment analysis. Males attained a maximum age of 13 years, while 17-year-old females were found. Several growth models were fitted and compared for both size and weight at age data, showing that even though this is a small sized species, it has a relatively slow growth rate. This species matures late and at a relatively large size: at 86.81% and 79.40% of the maximum observed sizes and at 58.02% and 54.40% of the maximum observed ages for males and females, respectively. It has a low fecundity, with a mean ovarian fecundity of 10.44 oocytes per reproductive cycle. The estimated parameters indicate that this species has a vulnerable life cycle, typical of deep water squalid sharks. Given the high fishing pressures that it is suffering in the NE Atlantic, the smooth lantern shark may be in danger of severe declines in the near future. (c) 2007 Elsevier B.V. All rights reserved.

The Metapopulation Dynamics of an Infectious Disease: Tuberculosis in Possums

An SEI metapopulation model is developed for the spread of an infectious agent by migration. The model portrays two age classes on a number of patches connected by migration routes which are used as host animals mature. A feature of this model is that the basic reproduction ratio may be computed directly, using a scheme that separates topography, demography, and epidemiology. We also provide formulas for individual patch basic reproduction numbers and discuss their connection with the basic reproduction ratio for the system. The model is applied to the problem of spatial spread of bovine tuberculosis in a possum population. The temporal dynamics of infection are investigated for some generic networks of migration links, and the basic reproduction ratio is computed—its value is not greatly different from that for a homogeneous model. Three scenarios are considered for the control of bovine tuberculosis in possums where the spatial aspect is shown to be crucial for the design of disease management operations

Managing moose harvests by the seat of your pants

Moose populations are managed for sustainable yield balanced against costs caused by damage to forestry or agriculture and collisions with vehicles. Optimal harvests can be calculated based on a structured population model driven by data on abundance and the composition of bulls, cows, and calves obtained by aerial-survey monitoring during winter. Quotas are established by the respective government agency and licenses are issued to hunters to harvest an animal of specified age or sex during the following autumn. Because the cost of aerial monitoring is high, we use a Management Strategy Evaluation to evaluate the costs and benefits of periodic aerial surveys in the context of moose management. Our on-the-fly "seat of your pants" alternative to independent monitoring is management based solely on the kill of moose by hunters, which is usually sufficient to alert the manager to declines in moose abundance that warrant adjustments to harvest strategies. Harvests are relatively cheap to monitor; therefore, data can be obtained each year facilitating annual adjustments to quotas. Other sources of "cheap" monitoring data such as records of the number of moose seen by hunters while hunting also might be obtained, and may provide further useful insight into population abundance, structure and health. Because conservation dollars are usually limited, the high cost of aerial surveys is difficult to justify when alternative methods exist. © 2012 Elsevier Inc.

Genetic Structure of Cochliobolus sativus Populations Sampled from Roots and Leaves of Barley and Wheat in North Dakota

Common root rot (CRR) and spot blotch, caused by Cochliobolus sativus (Ito and Kurib.) Drechsl. ex Dast., are important diseases of barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) worldwide. However, the population biology of C. sativus is still poorly understood. In this study, the genetic structure of three C. sativus populations, consisting of isolates sampled respectively from barley leaves (BL), barley roots (BR) and wheat roots (WR) in North Dakota, was analysed with amplified fragment length polymorphism (AFLP) markers. A total of 127 AFLP loci were generated among 208 C. sativus isolates analysed with three primer combinations. Gene diversity (H = 0.277-0.335) were high in all three populations. Genetic variation among C. sativus individuals within population accounted for 74%, whereas 26% of the genetic variation was explained among populations. Genetic differentiation was high (empty set PT = 0.261, corrected G ''(st)= 0.39), whereas gene flow (Nm) ranged from 1.27 to 1.56 among the three populations analysed. The multilocus linkage disequilibrium (LD) ((r) over bard = 0.0760.117) was moderate in C. sativus populations. Cluster analyses indicate that C. sativus populations differentiated according to the hosts (barley and wheat) and tissues (root and leaf) although generalists also exist in North Dakota. Crop breeding may benefit from combining genes for resistance against both specialists and generalists of C. sativus.

Genetic Structure of Cochliobolus sativus Populations Sampled from Roots and Leaves of Barley and Wheat in North Dakota

Common root rot (CRR) and spot blotch, caused by Cochliobolus sativus (Ito and Kurib.) Drechsl. ex Dast., are important diseases of barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) worldwide. However, the population biology of C. sativus is still poorly understood. In this study, the genetic structure of three C. sativus populations, consisting of isolates sampled respectively from barley leaves (BL), barley roots (BR) and wheat roots (WR) in North Dakota, was analysed with amplified fragment length polymorphism (AFLP) markers. A total of 127 AFLP loci were generated among 208 C. sativus isolates analysed with three primer combinations. Gene diversity (H = 0.277-0.335) were high in all three populations. Genetic variation among C. sativus individuals within population accounted for 74%, whereas 26% of the genetic variation was explained among populations. Genetic differentiation was high (empty set PT = 0.261, corrected G ''(st)= 0.39), whereas gene flow (Nm) ranged from 1.27 to 1.56 among the three populations analysed. The multilocus linkage disequilibrium (LD) ((r) over bard = 0.0760.117) was moderate in C. sativus populations. Cluster analyses indicate that C. sativus populations differentiated according to the hosts (barley and wheat) and tissues (root and leaf) although generalists also exist in North Dakota. Crop breeding may benefit from combining genes for resistance against both specialists and generalists of C. sativus.

Computational Methods for Detecting Large-Scale Chromosome Rearrangements in SNP Data

Large-scale chromosome rearrangements such as copy number variants (CNVs) and inversions encompass a considerable proportion of the genetic variation between human individuals. In a number of cases, they have been closely linked with various inheritable diseases. Single-nucleotide polymorphisms (SNPs) are another large part of the genetic variance between individuals. They are also typically abundant and their measuring is straightforward and cheap. This thesis presents computational means of using SNPs to detect the presence of inversions and deletions, a particular variety of CNVs. Technically, the inversion-detection algorithm detects the suppressed recombination rate between inverted and non-inverted haplotype populations whereas the deletion-detection algorithm uses the EM-algorithm to estimate the haplotype frequencies of a window with and without a deletion haplotype. As a contribution to population biology, a coalescent simulator for simulating inversion polymorphisms has been developed. Coalescent simulation is a backward-in-time method of modelling population ancestry. Technically, the simulator also models multiple crossovers by using the Counting model as the chiasma interference model. Finally, this thesis includes an experimental section. The aforementioned methods were tested on synthetic data to evaluate their power and specificity. They were also applied to the HapMap Phase II and Phase III data sets, yielding a number of candidates for previously unknown inversions, deletions and also correctly detecting known such rearrangements.

Monte-Carlo estimation of time-dependent statistical characteristics of random dynamical systems

The problem of estimating the time-dependent statistical characteristics of a random dynamical system is studied under two different settings. In the first, the system dynamics is governed by a differential equation parameterized by a random parameter, while in the second, this is governed by a differential equation with an underlying parameter sequence characterized by a continuous time Markov chain. We propose, for the first time in the literature, stochastic approximation algorithms for estimating various time-dependent process characteristics of the system. In particular, we provide efficient estimators for quantities such as the mean, variance and distribution of the process at any given time as well as the joint distribution and the autocorrelation coefficient at different times. A novel aspect of our approach is that we assume that information on the parameter model (i.e., its distribution in the first case and transition probabilities of the Markov chain in the second) is not available in either case. This is unlike most other work in the literature that assumes availability of such information. Also, most of the prior work in the literature is geared towards analyzing the steady-state system behavior of the random dynamical system while our focus is on analyzing the time-dependent statistical characteristics which are in general difficult to obtain. We prove the almost sure convergence of our stochastic approximation scheme in each case to the true value of the quantity being estimated. We provide a general class of strongly consistent estimators for the aforementioned statistical quantities with regular sample average estimators being a specific instance of these. We also present an application of the proposed scheme on a widely used model in population biology. Numerical experiments in this framework show that the time-dependent process characteristics as obtained using our algorithm in each case exhibit excellent agreement with exact results. (C) 2010 Elsevier Inc. All rights reserved.

Internationales Otolithen-Symposium in Australien

The Third International Symposium on Fish Otolith Research and Application in Townsville, Australia, from 11 to 16 July 2004, gathered around 300 scientists from 30 nations (http://www.otolith2004.com). Mayor topics were: structure of otoliths and function; micro-Chemitry and composition; determination of age and growth and their validation; de-termination of age in fish from tropical habitats; influence of climate, ecology and population biology; statistik and modelling; stock assessment and fishery management; quality control in institutions carrying out age determinations, and data processing; and development of technologies. The symposium was preceeded by a workshop at the James Cook University, Townsville, to enhance the knowledge and skill of participants in theoretrical and practical aspects for prearation of otoliths and interpretation of annuli; difficulties in interpreting age in tropical fish; daily increments as well as shape and image analysis.

Avian piscivores: basis for policy.

In Britain, many birds eat fish in fresh waters but only three species, cormorant, red-breasted merganser and goosander, are commonly perceived to present serious problems for freshwater fisheries. Complaints are mainly that cormorants eat large fish and that all three bird species eat so many juvenile fish, that there are subsequently fewer fish to be harvested or angled, but also that persistent predation by birds changes fish behaviour so that they are less 'catchable'. To this end, this report reviews existing information on the current status, foraging ecology, and population biology of the three bird species as background to their potential impact on fisheries. Discusses fish population dynamics within the context of predation effects. Reviews existing experimental evidence for impacts on fish populations and fisheries; and describes current legislation, discusses potential criteria for serious damage to a fishery, and suggests ways forward for NRA policy and research.