The dark side of an island radiation: systematics and evolution of troglobitic spiders of the genus Dysdera Latreille (Araneae : Dysderidae) in the Canary Islands

2007 ◽  
Vol 21 (6) ◽  
pp. 623 ◽  
Author(s):  
Miquel A. Arnedo ◽  
Pedro Oromí ◽  
Cesc Múrria ◽  
Nuria Macías-Hernández ◽  
Carles Ribera
Keyword(s):  
Body Size ◽  
Molecular Phylogeny ◽  
Canary Islands ◽  
Direct Evidence ◽  
Prey Capture ◽  
Dark Side ◽  
Additional Species ◽  
Local Adaptations ◽  
Different Levels ◽  
Subterranean Environment

The spider genus Dysdera Latreille is an excellent model for the study of the evolution of cave life: ten species are known to exist exclusively in the subterranean environment of the Canary Islands, where the genus has undergone local diversification. In the present paper, two new troglobitic species (Dysdera madai, sp. nov. and D. sibyllina, sp. nov.) and the previously unknown sex of five additional species are described and illustrated: the males of D. gollumi Ribera & Arnedo, 1994, D. hernandezi Arnedo & Ribera, 1999 and D. labradaensis Wunderlich, 1991; and the females of D. andamanae Arnedo & Ribera, 1997 and D. gibbifera Wunderlich, 1991. The first direct evidence of troglobitic members of Dysdera in micro- and mesocaverns are reported. The evolution of cave life as hypothesised following a combined morphological and molecular phylogeny is investigated. Troglobitic Canarian Dysdera species have colonised the underground on eight independent occasions. The Dysderidae groundplan represents a preadaptation to cave life and has facilitated the colonisation of caves. Canarian members of Dysdera have a predominantly parapatric mode of speciation, although postspeciation changes in distribution may have obscured allopatric processes. Eye regression and, to a lesser extent, larger body size and appendage elongation characterise troglobitic species. The different levels of troglobiomorphism are interpreted as local adaptations to heterogeneous subterranean conditions. The high levels of sympatry among troglobites are explained by trophic segregation and changes in prey capture strategy were involved in the single identified case of subterranean speciation in the group.

scholarly journals Scaling the feeding mechanism of the largemouth bass (Micropterus salmoides): motor pattern

1995 ◽  
Vol 198 (5) ◽  
pp. 1161-1171 ◽  
Author(s):  
P Wainwright ◽  
B Richard
Keyword(s):  
Body Size ◽  
Largemouth Bass ◽  
Standard Length ◽  
Prey Capture ◽  
Micropterus Salmoides ◽  
Motor Pattern ◽  
Onset Time ◽  
Small Fish ◽  
Scaling Effects ◽  
Emg Signal

We present the first analysis of scaling effects on the motor pattern of a feeding vertebrate. Data are presented for the effects of body size on the pattern of activity in four head muscles during prey capture in the largemouth bass, Micropterus salmoides. Electromyographic (EMG) recordings were made from three expansive-phase muscles (the epaxialis, the sternohyoideus and the levator arcus palatini) and one compressive-phase muscle (the adductor mandibulae), during the capture of small fish prey. Recordings were made of 181 prey-capture events from 19 bass that ranged in size from 83 to 289 mm standard length. We measured seven variables from the myogram of each capture to quantify the temporal pattern of muscle activation, including the duration of activity in each muscle and the onset time of each muscle, relative to the onset of the sternohyoideus muscle. Regressions of the mean value of each variable for the 19 individuals on standard length revealed that only the onset time of the adductor mandibulae changed with fish body size. The increase in onset time of the adductor muscle appears to reflect the longer time taken to open the mouth fully in larger fish. Other research shows that the kinematics of the strike in this species slows significantly with increasing body size. The combined results indicate that the duration of the EMG signal is not directly correlated with the duration of force production in muscles when compared between fish of different sizes. The lack of scaling of burst duration variables suggests that the reduced speeds of prey-capture motion are explained not by changes in the envelope of muscle activity, but rather by the effects of scale on muscle contractile kinetics. These scaling effects may include changes in the relative resistance of the jaw and head structures to movement through water and changes in the intrinsic contractile properties of the muscles of the feeding apparatus.

scholarly journals Guppies prefer to follow large (robot) leaders irrespective of own size

2018 ◽  
Author(s):  
David Bierbach ◽  
Hauke J. Mönck ◽  
Juliane Lukas ◽  
Marie Habedank ◽  
Pawel Romanczuk ◽  
...  
Keyword(s):  
Body Size ◽  
Risk Taking ◽  
Poecilia Reticulata ◽  
Direct Evidence ◽  
Behavioral Patterns ◽  
Behavioral Differences ◽  
Leaders And Followers ◽  
Biomimetic Robotic Fish ◽  
Risk Taking Behavior ◽  
Swimming Capacity

AbstractBody size is often assumed to determine how successful an individual can lead others with larger individuals being more likely to lead than smaller ones. However, direct evidence for such a relation is scarce. Furthermore, even if larger individuals are more likely to lead, body size correlates often with specific behavioral patterns (e.g., swimming capacity) and it is thus unclear whether larger individuals are more often followed than smaller ones because they are larger or because they behave in a certain way. To control for behavioral differences among differentially-sized leaders, we used biomimetic robotic fish – Robofish – of different sizes. Robofish is accepted as a conspecific by live guppies (Poecilia reticulata) and provides standardized behaviors irrespective of its size. We specifically asked whether larger leaders are preferentially followed when behavior is controlled for and whether the preferences of followers depend on their own body size or their risk taking behavior (‘boldness’). We found that live guppies followed larger Robofish leaders closer than smaller ones and this pattern was independent of the followers’ own body size as well as risk-taking behavior. This is the first study that shows a ‘bigger is better’ pattern in leadership in shoaling fish that is fully independent of behavioral differences between differentially-sized leaders and followers’ own size and personality.

Sense of Coherence and Ego-Resiliency as Predictors of Maladaptive Coping Among Juveniles With Different Levels of Delinquency

2021 ◽  
pp. 0306624X2110491
Author(s):  
Karol Konaszewski ◽  
Małgorzata Niesiobędzka
Keyword(s):  
Sense Of Coherence ◽  
Family Court ◽  
Dark Side ◽  
Critical Ratio ◽  
Ratio Test ◽  
Maladaptive Coping ◽  
Emotional Style ◽  
The Impact ◽  
Different Levels ◽  
Ego Resiliency

The purpose of the study is to determine the role of the sense of coherence and ego-resiliency as buffers for maladaptive coping among juveniles with different levels of delinquency. The study included 561 juveniles referred by a family court to youth education or probation centers throughout Poland. We used SEM to search for relations between variables and the critical ratio test for differences between groups. The results demonstrate that in both groups, the relationships between the components of the sense of coherence and the emotional style were negative. In both groups, the sense of comprehensibility was significantly associated with the search for social contacts. The impact of ego-resiliency on social-diversion coping was significantly stronger for the group with high compared with low demoralization. The study demonstrate that juveniles with a high degree of delinquency are more prone to emotion-oriented coping. Both groups of juveniles use two types of avoidance style to a similar extent. The results show that the stronger the sense of coherence, the less often juveniles cope with stress by reducing emotional tension and by escaping into substitute activities. Furthermore, our findings reveal the dark side of ego-resiliency.

Annual energy intake and early post-partum performance of beef heifers differing in body size and milk potential

1996 ◽  
Vol 1996 ◽  
pp. 134-134
Author(s):  
S. Yildiz ◽  
K.D. Sinclair ◽  
F.E. Gebbie ◽  
P.J. Broadbent ◽  
J.S.M. Hutchinson
Keyword(s):  
Body Size ◽  
Energy Intake ◽  
Post Partum ◽  
Ovarian Activity ◽  
Term Study ◽  
Beef Cow ◽  
Long Term Study ◽  
The Uk ◽  
Different Levels

As part of a long term study to assess the suitability of beef cow genotypes, differing in body size and milk potential, for different forage environments within the UK, eight purebred Aberdeen Angus (AA; considered to be small and relatively non-milky) and eight purebred Simmental (Sm; considered to be large and relatively milky) heifers were placed on different levels of annual energy intake. Changes in body composition and milk yield were recorded and related to early post partum ovarian activity.

A new species of the Pristimantis orestes group (Amphibia: Strabomantidae) from the high Andes of Ecuador, Reserva Mazar

Zootaxa ◽  
2013 ◽  
Vol 3616 (4) ◽  
pp. 345-356 ◽  
Author(s):  
JUAN M. GUAYASAMIN ◽  
ALEJANDRO F. ARTEAGA
Keyword(s):  
New Species ◽  
Body Size ◽  
Molecular Phylogeny ◽  
Mitochondrial Gene ◽  
Small Body ◽  
Dominant Frequency ◽  
Small Body Size ◽  
Adult Males ◽  
Adult Females ◽  
A New Species

We describe a new Pristimantis from La Libertad and Rumiloma, Reserva Mazar, Andes of Southeastern Ecuador, at elevations between 2895–3415 m. This species is assigned to the P. orestes group, from whose members it differs by its small body size (adult males ≤ 18.1 mm; adult females ≤ 23.7 mm), usually reticulated ventral pattern, and visible tympanum. The vocalization of the new species consists of a series of calls; each call is composed by a pulsed, non-modulated note in frequency, and with a dominant frequency of 3122–3171 Hz. A molecular phylogeny based on a fragment of the mitochondrial gene 12S shows that the new species is sister to Pristimantis simonbolivari.

Threat-level-dependent manipulation of signaled body size: dog growls’ indexical cues depend on the different levels of potential danger

2016 ◽  
Vol 19 (6) ◽  
pp. 1115-1131 ◽  
Author(s):  
Anna Bálint ◽  
Tamás Faragó ◽  
Ádám Miklósi ◽  
Péter Pongrácz
Keyword(s):  
Body Size ◽  
Potential Danger ◽  
Threat Level ◽  
Different Levels

scholarly journals New records in vascular plants alien to Tenerife (Spain, Canary Islands)

2021 ◽  
Vol 9 ◽  
Author(s):  
Filip Verloove
Keyword(s):  
Canary Islands ◽  
Vascular Plants ◽  
New Records ◽  
Eucalyptus Camaldulensis ◽  
Psidium Guajava ◽  
Grevillea Robusta ◽  
Additional Species ◽  
Commelina Benghalensis ◽  
Lippia Alba ◽  
First Time

Recent fieldwork by the author in Tenerife, mostly between 2014 and 2019, yielded new records of alien vascular plants. Fifteen taxa (Acacia decurrens, A. mearnsii, Caesalpinia pulcherrima, Ensete ventricosum, Eucalyptus camaldulensis subsp. arida, E. cladocalyx, Euryops chrysanthemoides, Ficus elastica, Lippia alba, Pavonia sepioides, Pittosporum tobira, Populus × canadensis, Pyrostegia venusta, Ruellia dipteracanthus and Wigandia kunthii) are reported for the first time from the Canary Islands. All were initially introduced on purpose, mostly as ornamentals, and recently started to escape from cultivation. Most of them are ephemerals or only locally established, but nearly all have the potential to naturalise in the future. Thirteen additional species are reported for the first time from Tenerife: Atriplex nummularia, Bellis perennis, Chenopodium probstii, Coccoloba uvifera, Commelina benghalensis, Cuphea hyssopifolia, Eragrostis virescens, Lemna minuta, Malvastrum corchorifolium, Plerandra elegantissima, Psidium guajava, Thunbergia alata and Urochloa subquadripara. Finally, some miscellaneous notes are provided on the presence of Balanites aegyptiaca, Callistemon viminalis, Grevillea robusta and Passiflora caerulea in Tenerife.

scholarly journals New records in vascular plants alien to Tenerife (Spain, Canary Islands)

2021 ◽  
Author(s):  
Filip Verloove
Keyword(s):  
Canary Islands ◽  
Vascular Plants ◽  
New Records ◽  
Eucalyptus Camaldulensis ◽  
Psidium Guajava ◽  
Grevillea Robusta ◽  
Additional Species ◽  
Commelina Benghalensis ◽  
Lippia Alba ◽  
First Time

Recent fieldwork by the author in Tenerife, mostly between 2014 and 2019, yielded new records of alien vascular plants. Seventeen taxa (Acacia decurrens, A. mearnsii, Brachychiton diversifolius, Caesalpinia pulcherrima, Ensete ventricosum, Eucalyptus camaldulensis subsp. arida, E. cladocalyx, Euryops chrysanthemoides, Ficus elastica, Lippia alba, Pavonia sepioides, Pittosporum tobira, Populus ×canadensis, Pyrostegia venusta, Ruellia dipteracanthus, Soleirolia soleirolii and Wigandia kunthii) are reported for the first time from the Canary Islands. All were initially introduced on purpose, mostly as ornamentals, and recently started to escape from cultivation. Most of them are ephemerals or only locally established but nearly all have the potential to naturalize in the future. Thirteen additional species are reported for the first time from Tenerife: Atriplex nummularia, Bellis perennis, Chenopodium probstii, Coccoloba uvifera, Commelina benghalensis, Cuphea hyssopifolia, Eragrostis virescens, Lemna minuta, Malvastrum corchorifolium, Plerandra elegantissima, Psidium guajava, Thunbergia alata and Urochloa subquadripara. Finally, some miscellaneous notes are provided on the presence of Balanites aegyptiaca, Callistemon viminalis, Grevillea robusta and Passiflora caerulea in Tenerife.

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