Macroevolution of Bold Color Patterns Across Teleostean Fishes

Fishes include some of the most visually striking vertebrate radiations and have repeatedly evolved bold color patterns, including bars, stripes, and spots. Such strong color patterns are hypothesized to provide multiple functions, including avoiding predation by obscuring recognizable features and communicating with others to secure territories and mates. Despite increasing focus on the functions and proximate drivers of color pattern evolution, the relevance of such pressures across broad taxonomic and time scales remain much less resolved. Using over 5000 species within the largest vertebrate radiation, teleostean fishes, I employ phylogenetic comparative methods to explore the lability and potential coevolutionary relationships between color pattern traits and habitat. Evolutionary models reveal that pattern traits are labile across fishes and transitions most often occur between patternless and non-contrast pattern species. I also find support for the long-held belief that reef fishes are more patterned than their non reef-dwelling marine relatives. Given the marked diversity of body shapes within this group and proposed functional relationships between fish body depth and stripe orientation on the body, I also test for relationships between color pattern types and body shape. I find differences in body shapes between species with singular versus repeating patterns, such as single and multiple stripes, suggesting potential coevolution of color pattern and morphology over macroevolutionary scales. This study is a key step towards uncovering the story behind the persistence of bold color patterns in nature and provides insight into how evolutionary pressures shape color displays across deep time

Foraging ecology of Rhinolophus euryale unveiled by DNA metabarcoding

187 p.Saguzarren ekologia eta jokamoldea ulertzeko ezinbestekoa da beraien eta harrapakinen arteko elkarrekintza trofikoak identifikatzea. Nahiz eta saguzarren oinarrizko bazka-ekologia ezaguna izan (adb.: non eta zertaz bazkatzen diran), beraien bazka-nitxoaren inguruko zehaztasunak aztertzea metodologikoki guztiz mugatuta egon da. Testuinguru honetan, DNA metabarcoding delako teknika molekularrak saguzarren ekologian sakontzeko aukera berri bat eskaintzen du. Tesi honetan, Rhinolophus euryale eta R. mehelyi ferra-saguzarrak eredu hartuta, saguzarren bazka-ekologiaren inguruko hainbat galdera ekologiko ebatzi dira DNA metabarcodingaren bidez. Tesiaren lehenengo ikerketa-atalean paradigma ekologiko berri bat aurkezten da: R. euryale espeziearentzako harrapakin-eskuragarritasuna ez da bere ehiza-habitat egokien presentziarekin eta hauen kontserbazioarekin soilik bermatzen, hau da, hesi-bizi eta hostozabalen basoekin. Harrapakinek beraien bizi-fase desberdinak garatzeko beharrezkoak dituzten habitatak ere ezinbestekoak dira saguzarrentzat, nahiz eta habitat hauek ez dituzten bazkatzeko erabiltzen. Paradigma berri hau testatzeko, 56 R. euryaleren dieta espezie mailan zehaztu eta berau osatzen duten sits espezieen beldarren beharrizan ekologikoak bilatu dira bibliografian. Jandako espezie askoren larbek saguzarren ehiza-habitatak ez diren bestelako habitat batzuk behar dituzte beraien larba-fasea burutzeko, larreak eta belardiak esaterako. Gainera, larben beharrizan ekologikoak esangarriki aldatzen dira sasoitik sasoira. Beraz, R. euryaleren bazka-beharrizanak asetzeko ez dira nahikoa ehiza-habitat egokiak kontserbatzea paisai jakinean. Ehiza-habitatak bazkaz hornitzeko beharrezkoak diren gainerako eremuak ere guztiz beharrezkoak dira. Azken hauetan egindako edozein eraldaketak eragin zuzena izan dezake R. euryaleren bazka-ekologian. Gure emaitzen arabera, saguzarrak kontserbatzeko beharrezko neurriek ehiza habitatak barneratzeaz gain harrapakinen fase desberdinak garatzeko beharrezko elementuak barneratu beharko lituzkete ere. Sits-habitat-saguzar erlazioez gain, saguzarren bazka-ekologian eragina duen beste aldagai garrantzitsu bat ekologikoki antzekoak diren espezieen presentzia da. Testuinguru honetan, antzeko animalia espezie askoren koexistentzia ahalbidetzen duen mekanismo garrantzitsua da bazka-baliagaien banaketa. Saguzarretan, ordea, ez da ondo ezagutzen mekanismo honen garrantzia. Gainera, asko dira ekologikoki eta morfologikoki antzekoak diren eta eremu berdinean bizi diren saguzar espezieak. Honek beraien koexistentzia ahalbidetzen duten mekanismoen inguruko eztabaida piztu izan du komunitate zientifikoan aspaldidanik. Sentsu honetan, sinpatrian bizi diren espezie ahaideen nitxo-desberdintanek islatuko dituzte modu fidagarrienean koexistentzia ahalbidetzen duten mekanismoak (Adb.: bazka- edo habitat-banaketa). Tesiaren bigarren zati honetan DNA metabarcodingaren bidez ekologikoki oso antzekoak diren R. euryale eta R. mehelyi espezie ahizpen populazio sinpatriko baten dieta osaketa eta gainezarpena aztertu dira. Gainera, populazio honen inguruan daukagun ezagumendu ekologikoa oso zehatza da, dietaz gain bestelako ezaugarri ekologiko eta morfologikoak ikertu baitira tesi honen aurretik eginiko ikerketa-lan batean. Hortaz, populazio honek saguzarren koexistentziaren inguruko mekanismoak aztertzeko eredu ezinhobea eskaintzen du. Emaitzei dagokienez, bi saguzar espezieen dieta zoriz esperotakoa baino gehiago gainezartzen da. Gainera, sits arrunt berdinetan oinarritua dago bereziki. Sits-espezie hauek beste saguzar espezie askoren dietan behatu dira ere, saguzarren bazka-ekologian sits arruntek duten garrantzia azpimarratuz. Bestetik, behatutako dieta desberdintasunek saguzarrek sinpatrian duten habitat erabilera desberdintasuna islatzen dute: R. euryalek baso hostozabalei loturiko sits espezie espezialistak kontsumitu ditu batik bat, eta R. mehelyik, ordea, habitat irekiagoetako sitsak. Aldez aurretik eginiko ikerlanen arabera bi saguzar espezieen populazio alopatrikoek habitat erabilera oso antzekoak erakusten dituzte. Egoera sinpatrikoan ordea, habitat erabileraren banaketa garbi bat antzematen da, non R. euryalek baso hostozabalak erabiltzen dituen exklusiboki, eta R. mehelyik leku irekiagoak. Habitat-erabilera eredu hauekin eta lan honetan behatutako dietaren gainezarpen altuarekin batera, bi ferra-saguzar espezie hauen koexistentzia bazka-baliagaien banaketan baino, habitaten banaketan oinarritua dagoela ondorioztatzen dugu. Lan honek ferra-saguzarren koexistentzia ahalbidetzeko nitxoaren dimentsio espazialak, hau da, habitatak, eta sits espezie arruntek duten garrantzia azpimarratzen du. Tesiaren azkenengo atalean R. euryaleren bazka-nitxoaren malgutasuna eta harrapakinekin duen erlazio ebolutiboa aztertu dira. Bestetik, eskuragarri egon daitezkeen sitsen konposizio funtzionala aztertu da ere. Saguzarren ehiza-errentagarritasunaren ikuspuntutik, sitsek hainbat ezaugarri morfologiko, hegakera-modu, ihes- eta defentsa-mekanismo dituzte, baita saguzarren ultrasoinuak antzemateko gaitasuna ere. Ezaugarri guzti horien konbinazio desberdinek sitsen errentagarritasunean, eta beraz, saguzarren bazka-ekologian, eragin desberdina izan dezaketela argudiatzen dugu, baita R. euryale bezalako sits-espezialista batentzako ere. DNA metabarcodinga eta RLQ eta fourth-corner tresna estatistikoen bidez, sitsen errentagarritasunarekin erlazionatuta egon daitezkeen ezaugarriak erabili dira adin, sexu, sasoi eta kolonia desberdinetako saguzarren dieta eta eskuragarri dauden sitsen konposizioa aztertzeko. Lortutako emaitzen arabera, kontsumitutako sitsen eta eskuragarri daudenen masa eta hegakera-moduarekin erlazionatutako ezaugarriak esangarriki aldatzen dira sasoiaren arabera. Saguzar helduek hainbat sits-mota kontsumitu dituzte umatze-aurreko sasoian, sits lirain eta geldoak umatze sasoian eta energia askoko sits azkar eta maniobrakorrak umatze ostean. Emaitzek, denboran zehar gertatzen diren sits-moten aldaketei aurre egiteko R. euryalek duen malgutasun trofikoa adierazten dute. Beste alde batetik, saguzar gazteek helduekiko sits-mota esangarriki desberdinak kontsumitu dituzte maizago: espezie txiki, lirain eta geldoak. Helduek ordea, energetikoki errentagarriagoak diren sits pisutsu baina azkarrak kontsumitu dituzte sarriago. Adinarekin erlazionatutako desberdintasun hauek ale gazteen ehizarako esperientzia faltarekin egon daitezke erlazionatuta. Azkenik, sits-tinpanatuek dietaren gehiengoa osatu arren, arctiinoen taldeko tinpanatuak esperotakoa baino gutxiago kontsumitu dira. Argi-tranpen bidez hainbat arctiine espezie harrapatu izan badira ere, oso gutxitan behatu dira saguzarren dietan. Arctiinoen taldea ezaguna da saguzarrekiko garatu dituen ihes- eta defentsa-mekanismo konplexuengatik. Orain arte ordea, ez da arctiinoen eta saguzar-espezialisten arteko erlazioa behatu naturan. Emaitzek, arctiinoek R. euryale bezalako sitsetan espezializatutako saguzarrei ihes egiteko mekanismoak garatu dituztela iradokitzen dute. Ezaugarrietan oinarritutako dieta azterketek saguzarren bazka-ekologia eta erlazio ebolutiboak aztertzeko herraminta berritzailea eskaintzen dute, harrapakinen izen taxonomikoez haratago. Oro har, sitsetan espezializatutako R. euryaleren bazka-ekologia "hesi-bizietan ehizatu eta sitsetaz elikatzen da" baino konplexuagoa dela erakusten du tesi honek. Lortutako emaitzen arabera: 1) R. euryale paisaiaren elementu desberdinei lotuta dago eta elementu hauen garrantzia aldatu egiten da denboran zehar. 2) Ekologikoki antzekoak diren ferra-saguzarren koexistentzia ahalbidetzeko sits espezie arruntak eta ehiza-habitat dibertsoak beharrezkoak dira. 3) Eskuragarri dauden sitsen konposizio funtzionala sasoien arabera aldatzen da, baita saguzar helduen dietan ere. Honek sits-espezialista baten flexibilitate-trofikoa adierazten du eta inguruneko aldaketei aurre egiteko saguzarrak duen gaitasuna azpirratu. Gainera, oinarrizko harrapakinak bazka adinaren arabera aldatzen dira, ez taxonomikoki, harrapakin motei dagokienez baizik. Emaitza hauek harrapakinetan oinarritutako dieta azterketa berritzaileari esker lortu ahal izan dira. Tesi honek, oro har, saguzarren bazka-ekologia pentsatu baino konplexuagoa dela erakusten du, eta DNA metabarcodingaren bidez posible dela berau zehaztasunez ikertzea. Ikerketa ekologikoek eta espezieen kontserbaziora bideratutakoek konplexutasun guzti hau hartu beharko lukete kontutan etorkizuneko lanetarako

A learning gaussian process approach for maneuvering target tracking and smoothing

Model-based approaches for target tracking and smoothing estimate the infinite number of possible target trajectories using a finite set of models. This paper proposes a data-driven approach that represents the possible target trajectories using a distribution over an infinite number of functions. Recursive Gaussian process and derivative based Gaussian process approaches for target tracking and smoothing are developed, with online training and parameter learning. The performance evaluation over two highly maneuvering scenarios, shows that the proposed approach provides 80% and 62% performance improvement in the position and 49% and 22% in the velocity estimation, respectively, as compared to the best model-based filter

Distributed Target Engagement in Large-scale Mobile Sensor Networks

Sensor networks comprise an emerging field of study that is expected to touch many aspects of our life. Research in this area was originally motivated by military applications. Afterward sensor networks have demonstrated tremendous promise in many other applications such as infrastructure security, environment and habitat monitoring, industrial sensing, traffic control, and surveillance applications. One key challenge in large-scale sensor networks is the efficient use of the network's resources to collect information about objects in a given Volume of Interest (VOI). Multi-sensor Multi-target tracking in surveillance applications is an example where the success of the network to track targets in a given volume of interest, efficiently and effectively, hinges significantly on the network's ability to allocate the right set of sensors to the right set of targets so as to achieve optimal performance. This task can be even more complicated if the surveillance application is such that the sensors and targets are expected to be mobile. To ensure timely tracking of targets in a given volume of interest, the surveillance sensor network needs to maintain engagement with all targets in this volume. Thus the network must be able to perform the following real-time tasks: 1) sensor-to-target allocation; 2) target tracking; 3) sensor mobility control and coordination. In this research I propose a combination of the Semi-Flocking algorithm, as a multi-target motion control and coordination approach, and a hierarchical Distributed Constraint Optimization Problem (DCOP) modelling algorithm, as an allocation approach, to tackle target engagement problem in large-scale mobile multi-target multi-sensor surveillance systems. Sensor-to-target allocation is an NP-hard problem. Thus, for sensor networks to succeed in such application, an efficient approach that can tackle this NP-hard problem in real-time is disparately needed. This research work proposes a novel approach to tackle this issue by modelling the problem as a Hierarchical DCOP. Although DCOPs has been proven to be both general and efficient they tend to be computationally expensive, and often intractable for large-scale problems. To address this challenge, this research proposes to divide the sensor-to-target allocation problem into smaller sub-DCOPs with shared constraints, eliminating significant computational and communication costs. Furthermore, a non-binary variable modelling is presented to reduce the number of inter-agent constraints. Target tracking and sensor mobility control and coordination are the other main challenges in these networks. Biologically inspired approaches have recently gained significant attention as a tool to address this issue. These approaches are exemplified by the two well-known algorithms, namely, the Flocking algorithm and the Anti-Flocking algorithm. Generally speaking, although these two biologically inspired algorithms have demonstrated promising performance, they expose deficiencies when it comes to their ability to maintain simultaneous reliable dynamic area coverage and target coverage. To address this challenge, Semi-Flocking, a biologically inspired algorithm that benefits from key characteristics of both the Flocking and Anti-Flocking algorithms, is proposed. The Semi-Flocking algorithm approaches the problem by assigning a small flock of sensors to each target, while at the same time leaving some sensors free to explore the environment. Also, this thesis presents an extension of the Semi-Flocking in which it is combined with a constrained clustering approach to provide better coverage over maneuverable targets. To have a reliable target tracking, another extension of Semi-Flocking algorithm is presented which is a coupled distributed estimation and motion control algorithm. In this extension the Semi-Flocking algorithm is employed for the purpose of a multi-target motion control, and Kalman-Consensus Filter (KCF) for the purpose of motion estimation. Finally, this research will show that the proposed Hierarchical DCOP algorithm can be elegantly combined with the Semi-Flocking algorithm and its extensions to create a coupled control and allocation approach. Several experimental analysis conducted in this research illustrate how the operation of the proposed algorithms outperforms other approaches in terms of incurred computational and communication costs, area coverage, target coverage for both linear and maneuverable targets, target detection time, number of undetected targets and target coverage in noise conditions sensor network. Also it is illustrated that this algorithmic combination can successfully engage multiple sensors to multiple mobile targets such that the number of uncovered targets is minimized and the sensors' mean utilization factor sensor surveillance systems.is maximized

Orbital Debris-Debris Collision Avoidance

We focus on preventing collisions between debris and debris, for which there is no current, effective mitigation strategy. We investigate the feasibility of using a medium-powered (5 kW) ground-based laser combined with a ground-based telescope to prevent collisions between debris objects in low-Earth orbit (LEO). The scheme utilizes photon pressure alone as a means to perturb the orbit of a debris object. Applied over multiple engagements, this alters the debris orbit sufficiently to reduce the risk of an upcoming conjunction. We employ standard assumptions for atmospheric conditions and the resulting beam propagation. Using case studies designed to represent the properties (e.g. area and mass) of the current debris population, we show that one could significantly reduce the risk of nearly half of all catastrophic collisions involving debris using only one such laser/telescope facility. We speculate on whether this could mitigate the debris fragmentation rate such that it falls below the natural debris re-entry rate due to atmospheric drag, and thus whether continuous long-term operation could entirely mitigate the Kessler syndrome in LEO, without need for relatively expensive active debris removal.Comment: 13 pages, 8 figures. Accepted for publication in Advances in Space Researc

Optimal proportional-integral guidance with reduced sensitivity to target maneuvers

This paper proposes a new optimal guidance law based on proportional-integral (PI) concept to reduce the sensitivity to unknown target maneuvers. Compared to existing PI guidance laws, the proposed guidance command is derived in the optimal control framework while guaranteeing finite time convergence. The kinematics equation with respect to the zero-effortmiss (ZEM) is utilized and the integral ZEM is augmented as a new system state. The proposed guidance law is derived through the Schwarz's inequality method. The closed-form solution of proposed guidance law is presented to provide better insight of its properties. Additionally, the working principle of the integral command is investigated to show why the proposed guidance law is robust against unknown target accelerations. The analytical results reveal that the proposed optimal guidance law is exactly the same as an instantaneous direct model reference adaptive guidance law with a pre-specified reference model. The potential significance of the obtained results is that it can provide a point of connection between PI guidance laws and adaptive guidance laws. Therefore, it allows us to have better understanding of the physical meaning of both guidance laws and provides the possibility in designing a new guidance law that takes advantages of both approaches. Finally, the performance of the guidance law developed is demonstrated by nonlinear numerical simulations with extensive comparisons