DOCSLIB.ORG

The Conduit / Cul-De-Sac Hypothesis

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Conduit / Cul-De-Sac Hypothesis Spider Sperm Competition: The Conduit I Cul-De-Sac Hypothesis- A Route To Understanding Or A Dead End? By Paul James Yo ward DPhil. Thesis University of York Department of Biology September 1996 IMAGING SERVICES NORTH Boston Spa,Wetherby West Yorkshire, lS23 7BQ www.bl.uk PAGE NUMBERING AS ORIGINAL IMAGING SERVICESNORTH , Boston Spa,Wetherby West Yorkshire, LS23 7BQ www.bl.uk MISSING PAGES ARE UNAVAILABLE For Atnina 2 "Let the arachnologist watch his spiders in the life before he kills them to describe their carcasses, and the facts of structure will have a richer and more inspiring influence" "This is the reason why mothers are more devoted to their children than fathers: it is that they suffer more in giving them birth and are more certain that they are their own". Aristotle 4th Century BC (my emphasis) "...But this does not mean that the sperm from the first copulation is only instrumental in the fertilization of eggs. The sperms are retained in the female's spermathecee, and ... they are kept alive for long periods. Where several copulations take place the spermathecee will contain the sperms from each copulation mixed together, so, as spiders are polygamous, the males which mate most frequently will leave the largest number of offspring". Bristowe (1929) 3 0.0 Abstract This thesis is an evaluation of the hypothesis that the spennathecae of spiders affects the sperm precedence patterns in a predictable way (Austad 1984). Spermathecae come in two varieties: cul-de-sac and conduit. Cul-de-sac spennathecae, according to the hypothesis, are supposed to lead to second male sperm priority and conduit to first male sperm priority . The hypothesis was evaluated both directly and indirectly. Direct measurements were made of paternity in two species, Pholcus phalangioides and Tetragnatha montana, both of which are cul-de-sac species. It was found that P. phalangioides complies with the predicted precedence pattern and thus does not disprove the hypothesis. This second male priority pattern was despite a much shorter mating time by second mating males. In T. montana no precedence pattern was found, with equal likelihood of first or second mating males of gaining paternity. There was in T. montana a possible influence of the duration of mating affecting the precedence pattern, with longer mating males gaining a higher paternity no matter what order they mated in. It is discussed whether or not this is due to sperm loading or genitalic stimulation (Eberhard 1985). Indirect evaluation of the hypothesis included an analysis of mating behaviour in Zygiella x-notata which is a conduit species and was chosen as a comparison to the two cul-de-sac species. In Z. x-notata it was found that there was no difference between mating duration in first and second mating males. Mating persistence is thus the same in first and second mating males, suggesting that the males cannot detect that the female is a denuded 4 resource to second mating males. Hence first male priority may not be a factor in this species. Other indirect methods of evaluating the hypothesis involved charting the incidence of mate-guarding and mating-plugs. The expected pattern of mate-guarding was for conduit species to pre-mate guard and for cul-de-sac species to post-mate guard, because of the predicted sperm precedence patterns associated with the spermathecae. The predicted pattern was not found. In the case of mating-plugs it was predicted that these should be deployed by cul-de-sac species because it is in these species that second males are able to usurp paternity to a large extent. The opposite pattern was found with mating-plugs of various design being utilized by conduit species. It is postulated that mating-plugs are the mechanism by which first male priorities are established in conduit species, where this pattern is found. The absence of plugs in cul-de-sac species is possibly the reason that second males can cuckold. The additional data collected since 1984 reveal that patterns of paternity found in spiders seem to be more complex than was originally assumed by Austad (1984). Spermathecae are species-specific in character and this may reflect a species specificity in sperm precedence patterns. Thus the conduit I cul-de-sac dichotomy may not reflect a useful prediction of patternity patterns. 5 Table of contents 0.0 Abstract. 4 0.1 Acknowledgements. 6 1.0 General Introduction. 12 12 1.1 Sexual Selection And Spiders: Early Enthusiasm, Later Neglect. 12 1.1.1 Male-Male Competition. 15 1.1.2 Female Choice. 1.2 The Expansion Of Sexual Selection Into The Realm Of Primary Sexual Characteristics: A Controversial Chapter Of Sexual Imperialism. 16 16 1.2.1 Primary And Secondary Sexual Characters. 19 1.2.2 Sperm Competition. 1.2.3 Genitalia 20 1.3 Sperm Competition In Spiders: Sexual Selection Continuing After Copulation. 23 1.4 Spermathecal Architecture And Sperm Precedence Patterns: The History Of An Idea. 26 1.4.1 Insects. 26 1.4.2 Spiders. 28 1.5 The Entelegynae And Haplogynae: Shifting Definitions, Shifting Phylogeny. 34 6 1.6 Differences Between Spider And Insect Reproductive Systems: Importance To Sperm Competion And Spermathecal Influence Over Sperm Precedence. 36 41 1.7 Project Aims And Intoducing The Study Species. 2.0 Sperm Precedence Measurements In Pholcus phalangioides (Fuesslin) (Araneae, Pholcidae). 45 45 2.1 Introduction. 45 2.1.1 Distribution And Population Structure. 2.1.2 Phenology And Life History. 48 51 2.1.3 Morphology Of Body And Gametes. 2.1.4 Implications From The Biology Of Pholcus phalangioides For Sexual Selection. 53 55 2.2 Specimen Collection. 2.3 Mating Experiments. 56 2.3.1 Mating Observations And Data. 59 67 2.4 Rearing Methods. 70 2.4.1 Rearing Data. 2.5 Specimen Harvest, Storage And Preparation. 74 2.6 Electrophoresis. 75 2.6.1 Zymogram Interpretation. 78 89 2.6.2 Trends In P2 Data. 7 2.6.3 Incidence Of Multiple Paternity In The Wild And Genetic Variation At Collection Sites. 92 100 2.7 Discussion. 3.0 Sperm Precedence Measurements In Tetragnatha montana (Simon) (Araneae, Tetragnathidae). 105 105 3.1 Introduction. 105 3.1.1 Phylogeny. 106 3.1.2 Distribution, Habitat And Population Structure. 107 3.1.3 Phenology, Life History And Activity Periods. 108 3.1.4 Morphology Of Body, Spermathecae And Palps. 112 3.2 Mating Experiments. 113 3.3 Rearing. 114 3.4 Analysis Of Genetic And Paternity Data. 114 3.4.1 Genetic Data. 119 3.4.2 Wild Collected Specimens. 119 3.4.3 Paternity Data. 124 3.4.4 Wild Matings. 126 3.5 Mating Behaviour. 137 3.6 Discussion and Conclusions. 8 4.0 Mating Observations On Zygiella x-notata (Clerck 1757) (Araneae, Araneidae). 139 139 4.1 Introduction. 141 4.1.1 Relevant Natural History. 143 4.2 Mating Experiments. 150 4.3 Results. 150 4.3.1 Qualitative Results. 151 4.3.2Quantitative Results. 168 4.4 Discussion And Conclusions. 171 5.0 Sperm Competition And Its Evolutionary Consequences In The Spiders. 171 5.1 Introduction. 5.2 Incidence Of Polyandry And Other Preadaptations Towards High Levels Of Sperm Competition. 171 174 5.2.1 Sex Ratios. 175 5.2.2 Females' Sperm Storage Organs And Sperm Longevity. 176 5.3 A Re-evaluation Of Current Measurements OfP2' 5.4 Additional Sources Of Evidence Pertaining To Sperm Precedence: Peri-reproductive behaviours. 178 5.4.1 Mate Guarding. 178 182 5.4.2 Grasping Organs: A Novel Suggestion For Their Evolution. 9 5.4.3 Mating Plugs. 183 5.4.4 Single Palp Usage. 186 5.5 The Logic Of Stratification. 186 5.6 The Breakdown Of Stratification. 187 5.7 Sperm Utilization Strategies: Phyletic Limitation Or Adaptation? 189 225 6.0 General Discussion. 240 7.0 Glossary 243 8.0 Bibliograpby. 10 0.1 Acknowledgements I would like to acknowledge the assistance of a number of people in the completion of this project. Firstly I would like to thank Geoff Oxford for invaluable supervision, provision of facilities at the University of York and for securing a research studentship awarded by the Science and Engineering Research Council. Secondly I would like to thank those who responded to my requests for help on various questions pertaining to the thesis: Steven Austad, Dave Bilton, Jean Dennison, Raymond Forster, Rosemary Gillespie, Paul J. Watson, John Prenter, Nancy Reagan, Jeremy Searle, Mike Siva-Jothy, Dave Thompson, Soren Toft, Gabriele UbI and Fritz Vollrath. Thirdly I would like to thank everybody who sent me spider samples: A.E. ('Joddy') Cooper, Stan Dobson, Francis Farr-Cox, Chris Felton, Martin Filmer, E. Gardiner, Basil Harley, Dick Jones, Frank Katzer, Paul Lee, Cynthia Merrett, Andrew Sedman, the late Clifford Smith, Peter Smithers, Yvone Western and James Wright. Finally Iwould like to thank my parents who gave me both financial and emotional support during the completion of this thesis. 11 1.0 General Introduction! 1.1 Sexual Selection And Spiders: Early Enthusiasm, Later Neglect. Within two decades of Darwin's 'The Descent of Man, and Selection in Relation to Sex' (1871) the Peckhams were using spiders as study animals to investigate empirically sexual selection. Their work was summarised in two monographs on the Attidae (= Salticidae) (Peckham & Peckham 1889, 1890). In the years following this early enthusiasm, and up until the nineteen sixties, both araneology .and sexual selection were relatively neglected. In the case of araneology the neglect was a result of a lack of commercial interest, for sexual selection it was a lack of a theoretical framework. Despite the neglect a number of strands in spider sexual selection research have become evident since the nineteen sixties.
Load more

Recommended publications
  • QQR 7 Information Pack
    7th Quinquennial Review of Schedules 5 and 8 of the Wildlife and Countryside Act (1981) Information Pack (version 2.21) 14 May 2021 1 Version 2.2: Four reptiles and two seals removed from the EPS list (Annex 1); one EPS amphibian and two EPS reptiles that are all Endangered removed from Annex 2 – these species were included in Version 2 and/or 2.1 in error. See Annex 1 and Annex 2 for further information. 1. Introduction Every five years, the country nature conservation bodies (Natural England, Natural Resources Wales and NatureScot), working jointly through the UK Joint Nature Conservation Committee (JNCC), review Schedules 5 and 8 of the Wildlife and Countryside Act (WCA) 1981. The review will provide recommendations to the Secretary of State for the Environment, Food and Rural Affairs and to Ministers for the Environment in the Scottish Government and Welsh Government for changes to these schedules2. This is known as the Quinquennial Review (QQR). As part of the QQR, stakeholders are provided with the opportunity to propose changes to the species on the schedules. This Information Pack has been produced for the 7th QQR (QQR 7). It is important to note that this QQR differs from previous ones. The Information Pack explains the new selection criteria, provides a timetable, and explains the process to be used by stakeholders. Contact details of the QQR Inter-agency Group who are managing QQR 7, are listed in Section 5. In addition, the Information Pack provides details of how to complete the online survey through which stakeholders propose new species for inclusion on, or removal of existing species from Schedules 5 and 8, or propose a change to how species are protected on the schedules.
    [Show full text]
  • Sexual Selection Research on Spiders: Progress and Biases
    Biol. Rev. (2005), 80, pp. 363–385. f Cambridge Philosophical Society 363 doi:10.1017/S1464793104006700 Printed in the United Kingdom Sexual selection research on spiders: progress and biases Bernhard A. Huber* Zoological Research Institute and Museum Alexander Koenig, Adenauerallee 160, 53113 Bonn, Germany (Received 7 June 2004; revised 25 November 2004; accepted 29 November 2004) ABSTRACT The renaissance of interest in sexual selection during the last decades has fuelled an extraordinary increase of scientific papers on the subject in spiders. Research has focused both on the process of sexual selection itself, for example on the signals and various modalities involved, and on the patterns, that is the outcome of mate choice and competition depending on certain parameters. Sexual selection has most clearly been demonstrated in cases involving visual and acoustical signals but most spiders are myopic and mute, relying rather on vibrations, chemical and tactile stimuli. This review argues that research has been biased towards modalities that are relatively easily accessible to the human observer. Circumstantial and comparative evidence indicates that sexual selection working via substrate-borne vibrations and tactile as well as chemical stimuli may be common and widespread in spiders. Pattern-oriented research has focused on several phenomena for which spiders offer excellent model objects, like sexual size dimorphism, nuptial feeding, sexual cannibalism, and sperm competition. The accumulating evidence argues for a highly complex set of explanations for seemingly uniform patterns like size dimorphism and sexual cannibalism. Sexual selection appears involved as well as natural selection and mechanisms that are adaptive in other contexts only. Sperm competition has resulted in a plethora of morpho- logical and behavioural adaptations, and simplistic models like those linking reproductive morphology with behaviour and sperm priority patterns in a straightforward way are being replaced by complex models involving an array of parameters.
    [Show full text]
  • Prey of the Jumping Spider Phidippus Johnsoni (Araneae : Salticidae)
    Jackson, R. R . 1977 . Prey of the jumping spider Phidippus johnsoni (Araneae : Salticidae) . J. Arachnol. 5 :145-149 . PREY OF THE JUMPING SPIDER PHIDIPPUS JOHNSONI (ARANEAE : SALTICIDAE) Robert R. Jackson I Zoology Departmen t University of Californi a Berkeley, California 9472 0 ABSTRACT Field data indicate that P. johnsoni is an euryphagous predator, whose diet includes organisms (aphids, ants, opilionids) sometimes considered distasteful to spiders . Other spiders are preyed upon , including conspecifics. Prey size tends to be one quarter to three quarters the size of the predator . INTRODUCTION Since spiders are probably a dominant group of predators of insects (Bristowe, 1941 ; Riechert, 1974; Turnbull, 1973), there is considerable interest in their feeding ecology . Spiders have usually been considered to be euryphagous predators with a stabilizing , rather than regulative, effect on insect populations (Riechert, 1974) . However, informa- tion concerning the prey taken by particular spider species, in the field, is limited . Field studies by Edgar (1969, 1970), Robinson and Robinson (1970) and Turnbull (1960) are especially noteworthy . During the course of a study of the reproductive biology of Phidippus johnsoni (Peckham and Peckham) (Jackson, 1976), occasionally individuals of this species were found in the field holding prey in their chelicerae . Each prey discovered in this way i s listed in Table 1 . In addition, Ken Evans and Charles Griswold, who were familiar wit h this species, recorded observations of P. johnsoni with prey. (Their data are included in Table 1 .) These data came from a variety of habitats in western North America, most o f which have been described elsewhere (Jackson, 1976) .
    [Show full text]
  • Visual Perception in Jumping Spiders (Araneae,Salticidae)
    Visual Perception in Jumping Spiders (Araneae,Salticidae) A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy in Biology at the University of Canterbury by Yinnon Dolev University of Canterbury 2016 Table of Contents Abstract.............................................................................................................................................................................. i Acknowledgments .......................................................................................................................................................... iii Preface ............................................................................................................................................................................. vi Chapter 1: Introduction ................................................................................................................................................... 1 Chapter 2: Innate pattern recognition and categorisation in a jumping Spider ........................................................... 9 Abstract ....................................................................................................................................................................... 10 Introduction ................................................................................................................................................................ 11 Methods .....................................................................................................................................................................
    [Show full text]
  • SHORT COMMUNICATION a Vertebrate-Eating Jumping Spider
    2017. Journal of Arachnology 45:238–241 SHORT COMMUNICATION A vertebrate-eating jumping spider (Araneae: Salticidae) from Florida, USA Martin Nyffeler1, G. B. Edwards2 and Kenneth L. Krysko3: 1Section of Conservation Biology, Department of Environmental Sciences, University of Basel, CH-4056, Basel, Switzerland; E-mail: [email protected]; 2Curator Emeritus: Arachnida & Myriapoda, Florida State Collection of Arthropods, Gainesville, FL 32608, USA; 3Division of Herpetology, Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA Abstract. The salticid spider Phidippus regius C.L. Koch, 1846 is documented preying on small frogs (Hyla spp., Osteopilus septentrionalis) and lizards (Anolis carolinensis and Anolis sagrei) in Florida, USA. Female as well as male P. regius were engaged in feeding on this type of vertebrate prey. A total of eight incidents of P. regius devouring vertebrates have been witnessed in seven Florida counties. Furthermore, we report an incident of a large unidentified Phidippus sp. (possibly P. bidentatus F. O. Pickard-Cambridge, 1901) preying on an immature anole lizard in Costa Rica. P. regius, otherwise known to feed almost exclusively on insects and spiders, is one of the world’s largest salticid spiders reaching a maximum recorded body length of 2.2 cm. Most other salticid spiders appear to be too small in body size to overcome vertebrate prey. Vertebrate predation by salticid spiders has not been previously documented in the scientific literature. Together with Salticidae, spiders from 27 of 114 families (24%) are currently known to occasionally consume vertebrate prey. Keywords: Generalist predators, predation, prey, Dactyloidae, Hylidae, Southeastern USA With .5,900 described species, the jumping spider family (Salt- observations.
    [Show full text]
  • Biodiversity Audit and Tolerance Sensitivity
    October 2011 Biodiversity Audit and Tolerance Sensitivity Mapping for the Broads The Broads Biodiversity Audit is a Broads Authority initiative, undertaken by the University of East Anglia, supported by Natural England and working with the conservation organisations in the Broads area. Project manager Andrea Kelly, Senior Ecologist (Broads Authority) Steering group: Andrea Kelly (Broads Authority) Erica Murray (Broads Authority) Dorothy Casey (Suffolk Wildlife Trust) Martin Horlock (Norfolk Biodiversity Information Service) Phil Pearson (Royal Society for the Preservation of Birds) Scott Perkin (Norfolk Biodiversity Partnership) Martin Sanford (Suffolk Biological Records Centre) Hannah Wallace (Natural England) Stuart Warrington (National Trust) Citation: C. Panter, H. Mossman, P. M. Dolman (2011) Biodiversity Audit and Tolerance Sensitivity Mapping for the Broads. Broads Authority Report. University of East Anglia, Norwich. Published By: School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK ISBN: 978-0-9567812-1-5 © Copyright rests with the Broads Authority. Terms and Conditions for use of maps in this document i) You are granted a non-exclusive, royalty free, revocable licence solely to view the licensed data for non-commercial purposes for the period during which the Broads Authority makes it available. ii) You are not permitted to copy, sub licence, distribute, sell or otherwise make available the Licensed Data to third parties in any form iii) Third party rights to enforce the terms of this licence shall
    [Show full text]
  • Visual Reactions to Auditory Stimulus by the Jumping Spider Phidippus Princeps (Araneae, Salticidae)
    Visual reactions to auditory stimulus by the jumping spider Phidippus princeps (Araneae, Salticidae) Philip Denbaum Degree project in biology, Master of science (2 years), 2019 Examensarbete i biologi 45 hp till masterexamen, 2019 Biology Education Centre, Uppsala University, and Elizabeth Jakob lab, University of Massachusetts Supervisors: Elizabeth Jakob and Anders Berglund External opponent: Emilie Laurent & Julian Baur Table of contents Abstract 2 Introduction 3 Methods and Materials 5 Spider collection and care 5 General experimental setup 5 Overview of the eyetracker 5 Securing the spider 6 Aligning spider and finding retinas 6 Experiment 7 Data analysis 8 Statistical analyses 9 Results 10 Analysis 1 10 Analysis 2 13 Discussion 14 Future studies 15 Conclusions 16 Acknowledgements 16 References 17 Appendix 19 !1 Abstract Jumping spiders (Family Salticidae) are known for their exceptional vision, including color vision and spatial acuity. Salticids use their vision in many behaviors, including predation and courtship. Recently evidence of their ability to sense airborne vibrations, i.e. sound, was published. I used a specialized jumping-spider-specific eyetracker to study the visual reaction of the retinas of the jumping spider Phidippus princeps when exposed to the sound of a predator. I used a generic wasp sound, previously shown to induce a startle response, as stimulus and played it from different directions. The spiders showed strong reactions to the sound stimulus by large increases in retinal movement when exposed to the stimulus, and they showed no habituation to the stimulus over three rounds of exposure. However, I found no indication that the direction of retinal movement corresponded to the location of the sound source.
    [Show full text]
  • Natural Prey of the Jumping Spider Menemerus Semilimbatus (Hahn, 1827) (Araneae: Salticidae), with Notes on Its Unusual Predatory Behaviour
    EUROPEAN ARACHNOLOGY 2003 (LOGUNOV D.V. & PENNEY D. eds.), pp. 93100. © ARTHROPODA SELECTA (Special Issue No.1, 2004). ISSN 0136-006X (Proceedings of the 21st European Colloquium of Arachnology, St.-Petersburg, 49 August 2003) Natural prey of the jumping spider Menemerus semilimbatus (Hahn, 1827) (Araneae: Salticidae), with notes on its unusual predatory behaviour Åñòåñòâåííàÿ äîáû÷à ïàóêà ñêàêóí÷èêà Menemerus semilimbatus (Hahn, 1827) (Araneae: Salticidae) ñ çàìåòêàìè î åãî íåîáû÷íîì õèùíè÷åñêîì ïîâåäåíèè E.F. GUSEINOV Ý.Ô. ÃÓÑÅÉÍΠInstitute of Zoology, Azerbaijan Academy of Sciences, block 504, passage 1128, Baku 370073, Azerbaijan. email: [email protected] Èíñòèòóò çîîëîãèè ÍÀÍ Àçåðáàéäæàíà, êâàðòàë 504, ïðîåçä 1128, Áàêó 370073, Àçåðáàéäæàí. email: [email protected] ABSTRACT. Prey composition and the hunting behaviour of the jumping spider, Menemerus semilimbatus, which inhabits stone walls was studied. Less than 10% of the specimens in the population studied were observed feeding. Adult males fed significantly less frequently than adult females and juveniles. Diptera, the dominant prey group, accounted for more than 70% of all prey consumed. No other single prey type was present in significant numbers. M. semilimbatus adopts a specialized predatory behaviour towards flies that is unusual for salticids. This behaviour depends on how the fly is orientated towards the spider. If the fly is facing away from the spider, M. semilimbatus approaches it directly. When the fly is facing the spider, M. semilimbatus keeps its distance and encircles it until the prey is facing away from the spider. Only then, will the spider start to approach the fly directly. The specific habitat of M.
    [Show full text]
  • 196 Arachnology (2019)18 (3), 196–212 a Revised Checklist of the Spiders of Great Britain Methods and Ireland Selection Criteria and Lists
    196 Arachnology (2019)18 (3), 196–212 A revised checklist of the spiders of Great Britain Methods and Ireland Selection criteria and lists Alastair Lavery The checklist has two main sections; List A contains all Burach, Carnbo, species proved or suspected to be established and List B Kinross, KY13 0NX species recorded only in specific circumstances. email: [email protected] The criterion for inclusion in list A is evidence that self- sustaining populations of the species are established within Great Britain and Ireland. This is taken to include records Abstract from the same site over a number of years or from a number A revised checklist of spider species found in Great Britain and of sites. Species not recorded after 1919, one hundred years Ireland is presented together with their national distributions, before the publication of this list, are not included, though national and international conservation statuses and syn- this has not been applied strictly for Irish species because of onymies. The list allows users to access the sources most often substantially lower recording levels. used in studying spiders on the archipelago. The list does not differentiate between species naturally Keywords: Araneae • Europe occurring and those that have established with human assis- tance; in practice this can be very difficult to determine. Introduction List A: species established in natural or semi-natural A checklist can have multiple purposes. Its primary pur- habitats pose is to provide an up-to-date list of the species found in the geographical area and, as in this case, to major divisions The main species list, List A1, includes all species found within that area.
    [Show full text]
  • Life History of Phidippus Johnsoni (Araneae, Salticidae )
    Jackson, R . R . 1978 . The life history of Phidippus johnsoni (Araneae : Saltiicidae) . J. Arachnol. 6 :1-29 . LIFE HISTORY OF PHIDIPPUS JOHNSONI (ARANEAE, SALTICIDAE ) Robert R. Jackson ' Department of Zoology University of California, Berkeley Berkeley, California 9472 0 ABSTRACT In the laboratory, P. johnsoni oviposit successive batches of eggs with a trend toward a decrease i n both number of eggs and proportion of eggs that hatch in later batches . Approximately one month elapses between copulation and the first oviposition, and another month elapses between each succes- sive oviposition . Eggs hatch three weeks after oviposition, and spiderlings disperse from the materna l nest after another three weeks. Males mature earlier, pass through fewer molts, reach smaller adult siz e and have lesser adult longevity than females . There is considerable intrasexual variability in adult size , maturation time, and number of instars before reaching maturity . Males mature in 5 to 7 molts; females, 6 to 8 . Instar duration and variability in instar duration is greater in later than in earlier instars. Morphometric data from the laboratory were employed for estimating the number of molt s that spiders undergo in the Coastal Range of California . Spiders in nature matured later in the year an d probably passed through more molts before reaching maturity (6 to 8 for males ; 7 to 9 for females) than was the case for laboratory-reared spiders . Phenology and density were investigated in six popula- tions : two from the Coastal Range of California, two from Beach habitats (sea level, next to th e ocean) in California, and two from Alpine habitats (Sierra Nevada, California ; Rocky Mountains, Wyoming) .
    [Show full text]
  • Through Arthropod Eyes Gaining Mechanistic Understanding of Calcareous Grassland Diversity
    Through arthropod eyes Gaining mechanistic understanding of calcareous grassland diversity Toos van Noordwijk Through arthropod eyes Gaining mechanistic understanding of calcareous grassland diversity Van Noordwijk, C.G.E. 2014. Through arthropod eyes. Gaining mechanistic understanding of calcareous grassland diversity. Ph.D. thesis, Radboud University Nijmegen, the Netherlands. Keywords: Biodiversity, chalk grassland, dispersal tactics, conservation management, ecosystem restoration, fragmentation, grazing, insect conservation, life‑history strategies, traits. ©2014, C.G.E. van Noordwijk ISBN: 978‑90‑77522‑06‑6 Printed by: Gildeprint ‑ Enschede Lay‑out: A.M. Antheunisse Cover photos: Aart Noordam (Bijenwolf, Philanthus triangulum) Toos van Noordwijk (Laamhei) The research presented in this thesis was financially spupported by and carried out at: 1) Bargerveen Foundation, Nijmegen, the Netherlands; 2) Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research, Radboud University Nijmegen, the Netherlands; 3) Terrestrial Ecology Unit, Ghent University, Belgium. The research was in part commissioned by the Dutch Ministry of Economic Affairs, Agriculture and Innovation as part of the O+BN program (Development and Management of Nature Quality). Financial support from Radboud University for printing this thesis is gratefully acknowledged. Through arthropod eyes Gaining mechanistic understanding of calcareous grassland diversity Proefschrift ter verkrijging van de graad van doctor aan de Radboud Universiteit Nijmegen op gezag van de rector magnificus prof. mr. S.C.J.J. Kortmann volgens besluit van het college van decanen en ter verkrijging van de graad van doctor in de biologie aan de Universiteit Gent op gezag van de rector prof. dr. Anne De Paepe, in het openbaar te verdedigen op dinsdag 26 augustus 2014 om 10.30 uur precies door Catharina Gesina Elisabeth van Noordwijk geboren op 9 februari 1981 te Smithtown, USA Promotoren: Prof.
    [Show full text]
  • Araneae (Spider) Photos
    Araneae (Spider) Photos Araneae (Spiders) About Information on: Spider Photos of Links to WWW Spiders Spiders of North America Relationships Spider Groups Spider Resources -- An Identification Manual About Spiders As in the other arachnid orders, appendage specialization is very important in the evolution of spiders. In spiders the five pairs of appendages of the prosoma (one of the two main body sections) that follow the chelicerae are the pedipalps followed by four pairs of walking legs. The pedipalps are modified to serve as mating organs by mature male spiders. These modifications are often very complicated and differences in their structure are important characteristics used by araneologists in the classification of spiders. Pedipalps in female spiders are structurally much simpler and are used for sensing, manipulating food and sometimes in locomotion. It is relatively easy to tell mature or nearly mature males from female spiders (at least in most groups) by looking at the pedipalps -- in females they look like functional but small legs while in males the ends tend to be enlarged, often greatly so. In young spiders these differences are not evident. There are also appendages on the opisthosoma (the rear body section, the one with no walking legs) the best known being the spinnerets. In the first spiders there were four pairs of spinnerets. Living spiders may have four e.g., (liphistiomorph spiders) or three pairs (e.g., mygalomorph and ecribellate araneomorphs) or three paris of spinnerets and a silk spinning plate called a cribellum (the earliest and many extant araneomorph spiders). Spinnerets' history as appendages is suggested in part by their being projections away from the opisthosoma and the fact that they may retain muscles for movement Much of the success of spiders traces directly to their extensive use of silk and poison.
    [Show full text]