2,182 research outputs found
The Impact of Tax-Exempt Status: The Supply-Side Subsidies
Schmalbeck provides some background and history of the tax rules governing health care institutions and assess the significance of the subsidies these tax rules create
The evolution of harm: effect of sexual conflicts and population size
Conflicts of interest between mates can lead to the evolution of male traits reducing female fitness and to coevolution between the sexes. The rate of adaptation and counter-adaptation is constrained by the intensity of selection and its efficiency, which depends on drift and genetic variability. This leads to the largely untested prediction that coevolutionary adaptations such as those driven by sexual conflict should evolve faster in large populations where the response to selection is stronger and sexual selection is more intense. We test this using the bruchid beetle Callosobruchus maculatus, a species with well documented male harm. Whilst most experimental evolution studies remove sexual conflicts, we reintroduce sexual conflict in populations where it has been experimentally removed. Both population size and standing genetic variability were manipulated in a factorial experimental design. After 90 generations of relaxed conflict (monogamy), the reintroduction of sexual conflicts for 30 generations favoured males that harmed females and females more resistant to the genital damage inflicted by males. Large population size rather than high initial genetic variation allowed males to evolve faster and become more harmful. Sexual selection thus creates conditions where males benefit from harming females and this selection is more effective in larger populations
Köttkonsumtion och dess klimatpåverkan : hur mycket kött kan vi äta och av vilka djurslag för att det ska vara hållbart?
Klimatfrågan är en av vår tids största frågor. Om klimatförändringen får fortgå som trenden visar kan det få katastrofala konsekvenser i världen som till exempel utdöende av regnskogen, stigande vattennivåer, färskvattenbrist och mer extrema väderförhållanden. Jordbrukssektorn står globalt sett för upp mot 30 procent av växthusgasutsläppen vilket gör den till den enskilt största sektorn vad gäller växthusgasutsläpp. Inom jordbrukssektorn härrör mycket av utsläppen globalt sett från djurhållningen, orsaker till det är bland annat avskogning för att ge plats åt foderodling och bete, idisslares foderomvandling och användning av kväve i samband med foderodling. Ett sätt att minska utsläppen av växthusgaser är att minska köttkonsumtionen.
Syftet med det här examensarbetet är att besvara frågan Hur mycket kött kan vi äta och av vilka djurslag för att det ska vara hållbart? I detta ingår ett annat syfte som är att ge visioner av hur en ur klimatsynpunkt hållbar köttproduktion kan se ut i Sverige i framtiden.
Examensarbetet består av tre delar. Som bakgrund ges en litteraturstudie där bland annat jordbrukets samband med klimatförändringen tas upp. Den andra delen är ett visionsarbete. Två oberoende grupper fick diskutera sina uppfattningar om hur en ur klimatsynpunkt hållbar djurproduktion kan utformas och dessa diskussioner sammanfattades sedan till två visioner. Den tredje delen i examensarbetet består av beräkningar på köttkonsumtion och dess klimatpåverkan. Beräkningarna utgår till stor del från livscykelanalyser av olika djurslag och produktionssystem.
Jordbruket och djurhållningen som beskrivs i visionerna skiljer sig på vissa punkter drastiskt från dagens system. Det visar att det inte bara handlar om att förbättra och utföra klimatreducerade åtgärder på de system vi har idag, det krävs även stora förändringar som påverkar till exempel placering och omfattning av djurhållningen i Sverige. En stor förändring handlar om kretslopp. Båda visionerna ser kortare och tätare kretslopp och en foderproduktion som sker nära djuren. Det kommer att kräva omstruktureringar inom lantbruket och kommer till exempel att påverka vilka grödor som odlas på åkermarken. Andra gemensamma åtgärder i visionerna för att minska klimatpåverkan från djurproduktionen är att bättre anpassa produktionen till lokala förutsättningar och att utnyttja bete och livsmedelsrester mer i foderstaterna.
Enligt IPCC är 1600 kg CO2-ekv per person och år en hållbar nivå vad gäller utsläpp av växthusgaser. Dagens köttkonsumtion i Sverige kan inte anses vara hållbar ur klimatsynpunkt eftersom den enligt mina beräkningar genererar utsläpp på 838 kg CO2-ekv per person och år, den utgör alltså 52 procent av vad en individ kan tillåtas släppa ut. Det betyder att köttkonsumtionen i Sverige behöver minska. Jag anser att det är mer än en halvering av köttkonsumtionen i Sverige som måste till för att vi ska hamna på en hållbar nivå vad gäller utsläpp av växthusgaser. Hur stora utsläppen från köttkonsumtionen blir beror på hur köttet har producerats och av vilka djurslag. Positivt ur hållbarhetssynpunkt är att äta närproducerat kött från djur som bidragit till mer än att bara producera kött, till exempel kött från djur som gått på bete eller kött som kommer från mjölkproduktionen, det är också positivt att äta kött från djur som utfodrats med restprodukter. Kött från system där gödseln cirkuleras och blir till nytta för foderproduktionen är också positivt ur hållbarhetssynpunkt eftersom kvävenivåerna minskar när mindre nytt kväve förs in i systemet via handelsgödsel och baljväxter.Climate change is one of our times most important questions to be solved. If climate change
continues it can lead to extermination of species, melting of ice and lack of freshwater.
Agriculture is responsible for about 30 percent of the anthropogenic emissions of greenhouse
gases. From a global point of view a lot of the emissions from this sector come from animal
husbandry because of deforestation, fermentation and use of nitrogen in feed production. One
way to reduce our emissions of greenhouse gases is to eat less meat.
The aim with this thesis is to answer the question How much meat can we eat and which
species to have a sustainable meat consumption? Another aim is to give future visions about
how a sustainable meat production can look like in Sweden.
The thesis consists of three parts. The first part is a literatures study about among others the
connection between animal husbandry and climate change. The second part is about future
visions, I let researchers and other experts help me with this. Two independent groups were
allowed to discuss their ideas about sustainable meat production and then I summarized the
discussions to two future visions, one for each group. The third part in this thesis consists of
calculations of meat consumption and the climate impact it has. The calculations are based on
data from life cycle assessments.
The farming systems described in the future visions are in some statements very diverge from
the system we have today. That means that it is not enough to reduce climate impact from the
systems we have today. Big changes are needed, that for example influence location and size
of the animal production in Sweden. A big challenge is about recycling. Both of the visions
describe shorter and tighter rounds of nutrient in the future. This will demand great changes in
Swedish agriculture and will among others influence which kind of crops we produce on our
fields. The visions also describe better adaptation to local opportunities and a better use of
pasture and rest products in the fodder.
According to IPCC 1600 kg CO2-ekv per person and year is a sustainable level of greenhouse
gas emissions. Today’s meat consumption cannot be seen as sustainable though it generates
emissions of 838 kg CO2-ekv per person and year. This means that meat consumption in
Sweden have to decrease. To reach a sustainable level we need to reduce our meat
consumption with more than 50 percent
Functional equivalence of grasping cerci and nuptial food gifts in promoting ejaculate transfer in katydids.
The function of nuptial gifts has generated longstanding debate. Nuptial gifts consumed during ejaculate transfer may allow males to transfer more ejaculate than is optimal for females. However, gifts may simultaneously represent male investment in offspring. Evolutionary loss of nuptial gifts can help elucidate pressures driving their evolution. In most katydids (Orthoptera: Tettigoniidae), males transfer a spermatophore comprising two parts: the ejaculate-containing ampulla and the spermatophylax-a gelatinous gift that females eat during ejaculate transfer. Many species, however, have reduced or no spermatophylaces and many have prolonged copulation. Across 44 katydid species, we tested whether spermatophylaces and prolonged copulation following spermatophore transfer are alternative adaptations to protect the ejaculate. We also tested whether prolonged copulation was associated with (i) male cercal adaptations, helping prevent female disengagement, and (ii) female resistance behavior. As predicted, prolonged copulation following (but not before) spermatophore transfer was associated with reduced nuptial gifts, differences in the functional morphology of male cerci, and behavioral resistance by females during copulation. Furthermore, longer copulation following spermatophore transfer was associated with larger ejaculates, across species with reduced nuptial gifts. Our results demonstrate that nuptial gifts and the use of grasping cerci to prolong ejaculate transfer are functionally equivalent
Are geometric morphometric analyses replicable? Evaluating landmark measurement error and its impact on extant and fossil Microtus classification.
Geometric morphometric analyses are frequently employed to quantify biological shape and shape variation. Despite the popularity of this technique, quantification of measurement error in geometric morphometric datasets and its impact on statistical results is seldom assessed in the literature. Here, we evaluate error on 2D landmark coordinate configurations of the lower first molar of five North American Microtus (vole) species. We acquired data from the same specimens several times to quantify error from four data acquisition sources: specimen presentation, imaging devices, interobserver variation, and intraobserver variation. We then evaluated the impact of those errors on linear discriminant analysis-based classifications of the five species using recent specimens of known species affinity and fossil specimens of unknown species affinity. Results indicate that data acquisition error can be substantial, sometimes explaining >30% of the total variation among datasets. Comparisons of datasets digitized by different individuals exhibit the greatest discrepancies in landmark precision, and comparison of datasets photographed from different presentation angles yields the greatest discrepancies in species classification results. All error sources impact statistical classification to some extent. For example, no two landmark dataset replicates exhibit the same predicted group memberships of recent or fossil specimens. Our findings emphasize the need to mitigate error as much as possible during geometric morphometric data collection. Though the impact of measurement error on statistical fidelity is likely analysis-specific, we recommend that all geometric morphometric studies standardize specimen imaging equipment, specimen presentations (if analyses are 2D), and landmark digitizers to reduce error and subsequent analytical misinterpretations
The genetic architecture of fitness in a seed beetle: assessing the potential for indirect genetic benefits of female choice
<p>Abstract</p> <p>Background</p> <p>Quantifying the amount of standing genetic variation in fitness represents an empirical challenge. Unfortunately, the shortage of detailed studies of the genetic architecture of fitness has hampered progress in several domains of evolutionary biology. One such area is the study of sexual selection. In particular, the evolution of adaptive female choice by indirect genetic benefits relies on the presence of genetic variation for fitness. Female choice by genetic benefits fall broadly into good genes (additive) models and compatibility (non-additive) models where the strength of selection is dictated by the genetic architecture of fitness. To characterize the genetic architecture of fitness, we employed a quantitative genetic design (the diallel cross) in a population of the seed beetle <it>Callosobruchus maculatus</it>, which is known to exhibit post-copulatory female choice. From reciprocal crosses of inbred lines, we assayed egg production, egg-to-adult survival, and lifetime offspring production of the outbred F1 daughters (F1 productivity).</p> <p>Results</p> <p>We used the bio model to estimate six components of genetic and environmental variance in fitness. We found sizeable additive and non-additive genetic variance in F<sub>1 </sub>productivity, but lower genetic variance in egg-to-adult survival, which was strongly influenced by maternal and paternal effects.</p> <p>Conclusion</p> <p>Our results show that, in order to gain a relevant understanding of the genetic architecture of fitness, measures of offspring fitness should be inclusive and should include quantifications of offspring reproductive success. We note that our estimate of additive genetic variance in F<sub>1 </sub>productivity (<it>CV</it><sub><it>A </it></sub>= 14%) is sufficient to generate indirect selection on female choice. However, our results also show that the major determinant of offspring fitness is the genetic interaction between parental genomes, as indicated by large amounts of non-additive genetic variance (dominance and/or epistasis) for F<sub>1 </sub>productivity. We discuss the processes that may maintain additive and non-additive genetic variance for fitness and how these relate to indirect selection for female choice.</p
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